New ipod touch

Hello,
so i've got one.
someone is putting a bunch of cool apps and games on my ipod touch.
stuff that he is buying from his itunes account. when i get the ipod back, i have a feeling my itunes will wanna sync (therefore erase everything new on the ipod) i already checked "manually manage music" but is there anything else i need to do? if a window pops up saying "sync" or "transfer purchases" should i choose "transfer purchases"? will this copy all my apps/games/music from my touch and put it into my itunes account? any help is appreciated. thanks!