About mobile phone

Hi there, I will live in Japan for 1 year,I read alot of guides about mobile phone in Japan, but I couldn't understand.
Can anyone answer my question?

1) Which is used more? mail or sms?
2) How does this mail thing works? just like sms?
3) Does the phone mail works like a sms or it requires internet?
4) What would you recommend me to live there for a year? prepaid or make a plan?
5) Does the prepaid comes with internet if i ask? (I'm thinking in buying one of those flip cellphone)
6) Iphone mail is different from the mail of cellphones in japan? Can I also put a chip on my iphone to have internet on it too?

Than you, and english is not my native language.

1) Which is used more? mail or sms?

Mail, because its cheaper.

2) How does this mail thing works? just like sms?

yes, to the user its essentially the same. You just send to an email address rather than a phone number.

3) Does the phone mail works like a sms or it requires internet?

It requires data. Some phones may fall back to sms automatically if you don't have data available.

4) What would you recommend me to live there for a year? prepaid or make a plan?

Prepaid, it can be far cheaper (voice and mail only) or not so much (voice and data)

5) Does the prepaid comes with internet if i ask? (I'm thinking in buying one of those flip cellphone)

Depends on the provider. Some do, some don't.

6) Iphone mail is different from the mail of cellphones in japan?

If you mean imessages, it is virtually the same in Japan as email since sms isn't in as widespread use. Both imessage and regular mail use data on the iphone and are charged the same.

Can I also put a chip on my iphone to have internet on it too?

Maybe, depends if your phone is unlocked or not and what specific model iphone you have. If your phone can be used in Japan then check out the b-mobile offerings:

http://www.bmobile.ne.jp/lineup.html

more info:

http://www.japan-guide.com/e/e2223.html