[Orcrist]

First of all; go on vacation to Japan. Then decide wether its something for you or not.

As for some of your questions; a car? Just forget about it, a car in Japan is a pain. Unless you get to lease one.
Vegetables and fruits are relatively expensive.
As for rent; you need a Japanese person to be your guarantor if you want to rent a Japanese apartment. Otherwise you will have to resort to guesthouses/short term apartment aimed at foreigners. These are available between 50.000 yen/150.000 yen a month (the budget ones that is, you can get fancy short term apartments, 450.000 yen a month).

If you really wanna spend a few years in Japan think about being a JET or w/e. Its perfect for those who wanna experience Japan a few years, alot of issues are being taken care of.

My actual advice? Forget about Japan while planning your future and just start studying something you love. If you've completed that and still feel like you're missing out, go to Japan for a few months/become a JET for a few years. In the meanwhile; read up on Japanese culture. If you really think Japan is the place for you to be you should have little trouble working yourself through some Shinto books (Shinto - The Way Home by Thomas p. Kasulis is advisable for starters), some books that even more explain the functioning of Japanese society (for example The Book of 5 Rings), some books about Japanese history (dig up some quality articles about the Nanjing Massacre, and see if you can get a decent book about it aswell).
If you're done with that and thought it was boring as hell, reconsider going to Japan.