Blackberry question....?

I am going to buy a blackberry/blackjack/treo and was looking for some information, as I am pretty naive in this area. Will I be able to have multiple e-mail accounts forwarded to the phone? Also, which plan will I need, I don't plan on doing much web browsing, just using the e-mail/text features (mainly e-mail). Any opinions on which of the three is the best?Thanks!