You are correct. This project is with the support of MangaGamer. In real life, I've got a working relationship with them and was able to talk to them about getting this translated.
1. We're doing the translating and proofreading ourselves. Then it will be sent to BaseSon (the developers) to add into the game, then sent back to us to beta test.
2-a. If there are any errors after we test it, we will create a patch. No point doing a job if we don't do it well.
2-b. I assume MangaGamer would release any patch made for free, but I do believe anyone interested would have t purchase the game from MangaGamer to have it in English.
3. Yes. We are doing the translations for the companies involved to use.