returning to blackberry, questions

Hi, I just bought an 8830 we. I have an unlimited data plan with sprint and wanted to know if I used bb pin messenger while in the USA with a friend from Mexico, if that would incur additional roaming charges?
Also, I'm going on vacations to Mexico, would I be able to activate in Mex.? Like go to Telcel and get a sim card and get it to work with a Mexican phone number.
I have very high expectations about this phone. I had the 8703e years ago and I loved it but sprint's bb plans were expensive at that time so I decided to go with the palm treo and then palm centro (my current phone) but now that a lot of my friends have bb, I thought I'd try it again to be able to use bb messenger with my intrnational buddies but then again I wasn't sure if there would be an extra charge.
thanks!

1. No you will not be charged with roaming. As long as YOU are in the US you are ok.
2. Not sure (I have verizon)

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