jtteran welcome to pinstack!
the unlimited data plan covers emails, web browsing and pin messaging...so you are covered.
keep in mind that if you choose to use the OZ instant messaging client that came with your bb, it will deduct from your SMS package.
i would suggest using jivetalk, ramble or IM+ for im'ing (yahoo, gtalk, aim, msn messenger) because those programs use data...
let us know if you have anymore stupid questions j/k - no ?? is stupid, really!