[kcyk8703]

I have a buddy here who is under internship, you dont pick where you stay.
If you can speak at a native level of english then you can teach english. From the looks of your plan, your english ability is more than adequate.

If you plan on improving your japanese then joining a language school would be best. If you're really intent on working while in school pick your hours wisely, getting around is an energy burner.

You can find guest houses/dorms as low as 29 000yen/month (shared room) and as for food, Id average something like 10 000-15 000yen a month.
Transit will vary depending on how far you travel, you can get monthly payment passes between certain stops if your school/company supports it.

Anyway, lets just say Japan aint cheap, if you want to learn how to budget, this is the place to do it. Especially with Japans stable yen crushing many currencies like my canadian dollar.

(Theres no need to be rude, everyone has their own vision of japan and prepare differently or not at all.) There is no run-of-the-mill person either, everyone is different, always going to be someone more or less skilled than yourself.