What happens if I choose to transfer purchases

What happen was that my computer crashed leaving iTunes Wiped clean, but since everything was already on my iPod touch 4G I decided to use it as my computer until it was no longer needed. Now I have a new computer and the new iOS came out I thought that this would be a perfect time to go and plug up my iPod to a new computer, now when plugging into iTunes I know that there are two choices- the "erase and sync" or the "transfer purchases" - and because I have bought music and apps off of my iPod I would want to choose "transfer purchases" the one thing that is keeping me from doing it is the question of will it transfer over everything including music, free apps, paid apps, notes, and app data?