I know that the initial run of the game is supposed to have a big 500k mb or whatever download, but my Galaxy 7.0 tablet downloads it every time I open the game. Not a problem over wifi, but if I'm usjng 3g I am thinking my data plan will get used up quick. Just wanna know so I can avoid playing over 3g if this is the case.

Are you sure it's downloading something? The updater is supposed to run, during which time it checks to make sure your client version is current. If it's not current, it downloads what it needs to upgrade. If it is current, it verifies the files to make sure they haven't been tampered with and redownloads them if necessary.