I agree with whitey10tc.
I think howard forums is probably your best bet for MetroPCS. They have a forum dedicated to that carrier and I believe there are carrier specific ROMs for Metro. I suggest you do a lot of reading over there and ask users over there about what plans they use. I would think gps has been figured out by now.
Here is a link to the Metro Forum on Howard Forums:
http://howardforums.com/forumdisplay.php?f=335
Good Luck!