かずや

thanks a lot!

Yes. If you start with her route, You will be spoiled gravelly of all the stuff.
Trust me, let Alice for last and read Maia after the others three. My order will be exactly the same as the walkthrough:
Saki > Yayoi > Keiko > Maia > Alice 

Mochizuki Rina
Stage 1:
[Small Talk]
"I've decided I'm gonna become a good student." --> "I'll correct the school's moral values."
"Thoughts on all the cute new first years?" --> "I must talk to them nevertheless!"
[School Life] 
"How's your outside of school club thing?" --> "Maybe I'll start a Meteor Strike Club."
"I get so sleepy during afternoon classes." --> "I think it's classes being so boring that's the problem."
"Porn mags in the library. Wouldn't that be great?" --> "Think I'll donate some of my collection to the cause." (EXTRA)
"We NEED super carbonated drinks at this school! Agree?" --> "I think I'm gonna petition the school about this. They might actually pass it."
"Make any new friends lately?" --> "I guess you're just a natural at it."
[Weekends and Holidays]
"Isn't it tough working a part time job on the weekends?" --> "People who work jobs day in and day out really are amazing."
"Nothing more depressing than seeing flirty couples on weekends." --> "Does it not make you depressed any?"
"Don't you just hate doing nothing on weekends?" --> "I'm gonna change myself into the guy with plans every Sunday."
"Tips on how to spend my time productively on weekends?" --> "Could always just go do something with you."
Stage 2: 
[Hobbies]
"Do you ever think about getting really good at one type of game?" --> "There definitely are collectors"
"Any things you've been really into lately?" --> "Since you like it maybe I will."
"Know of any easy-to-pick-up hobbies?" --> "I'm gonna take candid shots of you starting tomorrow."
"How much money do you spend on your hobbies?" --> "The people who mess with motorcycles must spend like a fortune every month."
"I'm thinking of trying out fishing. What do you think?" --> "I know how you feel"
[Private Life]
"How many times do you clean your room per week?" --> "You're a clean freak! You're a legit clean freak!"
[Fitness]
"Do you play any sports other than tennis?" --> "Does lacrosse get that messy...?" (EXTRA)
[Future]
"Anything you wanna achieve before you graduate?" --> "That's the kinda answer I'd expect from you."
"What's your plan for the scholarship test?" --> "If only there was a test on having fun..."
"I wonder if it's better to have a lotta qualifications?" --> "I'll show them! I don't need qualifications to be something!"
"Do you have a hard time picturing where you'll be after graduation? I do." --> "No fair! Let me join in too!"
"Occupational aptitude tests are kind of fun" --> "Can't tell you." 
"Laugh at me if I graduate without even being able to find a girlfriend." --> "I'll cry." (EXTRA)
[Romance]
"Tell me what girls think of love." --> "Is that the suspension bridge effect?"
Stage 3:
[Hobbies 2]
"Do you have any surprising hobbies?" --> "Oh Mochizuki... That's so cute"
"Does bathing powder really work?" --> " You know what bathing powders are effective?"
"Do you go to bathhouses often?" --> "Swimming there feels hella good."
"Aren't the bottles for female cosmetics just so cute?" --> "Maybe I'll buy some."
"Tell me about girls and arcades." --> "Rhythm games are so embarrassing to play" (EXTRA)
Watch any good anime recently?" --> "Isn't Castanet Erect that old show?"
[Chatting]
"Too many commercials can legit ruin any show, don't you feel like?" --> "Alright, gimme one million yen and I'll get to work." (EXTRA)
"I really don't like panties you're meant to be able to see" --> "Spats are appealing in their own way."
[Romance 2] 
"What advice do you give a man after he gets rejected?" --> "If I were in that situation I'd level up and try again."
[Ask Me]
"Ask me something about my hobbies." --> "Probably fun songs."
"Ask me about my private life." --> "Definitely bread."
[Do something]
"Stare at her." --> "Mind if I give you a hug?"
"Smile at her." --> "I'm practicing my natural smile."
[Work]
"Can being a hard worker get you a raise?" --> "Someone as great as the noble Rina must only get the highest of wages."
----
Mochizuki's Third Event:
"Me too"
"Something swimming related."
----
Stage 4:
[Romance 3]
"I've been having a lotta fun talking to this certain someone lately." --> "I was thinking it so I figured I'd say it." (EXTRA)
"What do you think of controlling girlfriends?" --> "I wish people had more confidence to just say no to stuff like that."
"I feel like you worry about what you wear when you start crushing on someone." --> "I'm going to start wearing suits to school from now on." (EXTRA)
"Give me an example of the type of guy girls would see as a 'slob' " --> "I bath regularly I swear!"
"You can really tell who's good at romance and who isn't." --> "Can I fire a cupid beam full of love and hearts and kisses at you?"
[Looks]
"Appearance is just a matter of luck when you think about it." --> "You're really convincing, Mochizuki."
"Ever thought about getting plastic surgery?" --> "Your body is something like a gift from your parents."
"You ever gone to a thrift shop to buy clothes?" --> "Tell me where I go to get the good stuff."
"What's this whole 'cool-cute' thing?" --> "I feel like they should just pick cool or cute, one or the other."
"What do you think of guys who wax their hair?" --> "You could use a pompadour as a drill!"
"Is it true that you'll get dry skin if you don't wash out conditioner right away" --> "I've certainly learned something new today..."
[Hobbies 3]
"Have you ever had pickled celery?" --> "Same here."
"Can you make homemade soap?" --> "Lemme be your model next time you're making some soap."
"Do you count your daily calories?" --> "And so that's how they always keep themselves looking good..."
"What rice cookies would you recommend?" --> "Very refined."
"What's hyaluronic acid" --> "Does it do anything special if you drink it?"
"Pickled cucumber is just so simple and safe." --> "I"ll try asking my mom to make it."
[Chatting 2]
"I really wish they wouldn't rank everyone in our grade level with test scores." --> "So, we can say we did better than our peers?"
[Do something 2]
"Stare at her." --> "S-Say something..." (EXTRA)
"Smile at her." --> "You could say that."
[Trends]
"What do you do to keep up on fashion?" --> "At that point why not just create your own fashion trend?"
----
Once you reach Mochizuki's final event, you may hold her hand if you choose the correct options, detailed below:
"I was really worried you were gonna say yes." "I don't know" "Take her hand" ----
Stage 5:
"Confess"
Note: Confess before June 21th.
----
Rina's route first choice event:
"It was kinda exciting"
"I'll give you everything you want"
----
This Rina guide is based and tested by me, a Team Rina lover.
 

Yes, these two are already covered.
Yes. You need to confess before the time limit ends, obviously.
That's correct. Er... I guess I might include that? I honestly would prefer not to but as you will.
Okay. This was something I was going to try and test eventually, but I'm glad to know it does exist.

ok.. 
it says here that. 
1. you can pick what outfit/hairstyle when you enter separate routes.
2. if you pick the same girl over and over again it's still possible to enter her route even if you make mistakes on the choices.
3. if you can already confess to the girl you chose and yet you still haven't confessed to her you, you will land on a bad end once you meet 6/24
4. there's a jealousy event if you have a girl with lvl 4 affection and another girl with lvl 3 affection. (there's no cg so it's up to you whether you want to trigger that event or not.
5. if you press F12 you can make the girls naked. ( ͡° ͜ʖ ͡°) (it doesn't work on CG btw)

i left out some parts we already know. like once you get enough affection an event will trigger and the affection lvl will rise. and the topic choices will change once the lvl rises. and once you see all 4 events you can chose whether to confess or not.

ok.. 
it says here that. 
1. you can pick what outfit/hairstyle when you enter separate routes.
2. if you pick the same girl over and over again it's still possible to enter her route even if you make mistakes on the choices.
3. if you can already confess to the girl you chose and yet you still haven't confessed to her you, you will land on a bad end once you meet 6/24
4. there's a jealousy event if you have a girl with lvl 4 affection and another girl with lvl 3 affection. (there's no cg so it's up to you whether you want to trigger that event or not.
5. if you press F12 you can make the girls naked. ( ͡° ͜ʖ ͡°) (it doesn't work on CG btw)

i left out some parts we already know. like once you get enough affection an event will trigger and the affection lvl will rise. and the topic choices will change once the lvl rises. and once you see all 4 events you can chose whether to confess or not.

1 and 2 are about the same. I don't think it'll hurt you to pick another girl if the prefered one isn't avalible. There is a lot of time to get a girlfriend and that make me think the developers may thought you may want to interact with diferent heroines before to pick your favorite.  Also the game is based on love points so the developers have probably consider it could take you some time to get enought points unless you keep reloading if things didn't go your way.
You can pick to not see anyone when your prefered heroine isn't avalible in order to make a pure 100% experience of each route. This way when you go back and pick another heroine everything will still be new. It depend of how you like to play.

1. Bugger all. You are free to talk with whomever you like.
2. You do not.
3. Sod all. As far as I can tell, you become unable to further raise her affection.
In short, you only enter a route once you confess to a girl an nothing else matters.
 
There are, in each route, two sets of choices that affect the game:
I don't think the hidden route is a secret, though I'm not sure of when I'll get to it either.
You can probably tell this guide isn't complete, and honestly, I'm just not a very fast reader. It'll take me a while yet before I can get to all girls.

As for the walkthrough, there's one from the translator themselves. The walkthrough in question was only covered both of Midori's and Runa's routes though. It's still easy though to get other three routes even if the walkthrough didn't cover that. Here's the walkthrough in question below, and hope it'll be help for anyone else who play HatsuKoi.
 

Common route:
SAVE
Yukino route --> Childhood friend ero-DVD (don't feel like translating her other choices yet)
Runa route:
Kyou route:
Midori route:
Maya route --> Special effects(?) ero-DVD (don't feel like translating her other choices yet)
 
http://seiya-saiga.com/game/toneworks/hatsukoi.html