Seriouse trouble

[nanyjokerx10]

Soo im PLANING on going into the metro store and i Want them to flash my phone soo i can join my brothers family plan. But this morning the guy told me it would be a REALLY bad idea to do it because i would only get Texting and Phone calls. i tried to explain to him that i kno a site ( this site lol) that have guides on Getting the internet to work and and picture messageing.

But this guy was 100% sure that it would not work and i would have no internet.

My question is Can i go to the metro store, flash the phone and come back and use the guide "http://www.smartphonejunkie.com/newthread.php?do=newthread&f=502 "and will my internet work on the phone work? ???

P.S should i intall a Rom before or after i flash the phone AND Can i use the guide on this site to flash my phone and then go to the metro store and tell them my phone is allready flashed and tell them to add a line??