And from our playstyle (me: supporter/range, she: tank or engineer in other games) would you recommend certain classes? (I read stuff on various sites but I am not sure yet) Maybe you guys can give us some tips?
You: Sage/Sorcerer, or Commando/Mercenary
GF: Shadow/Assassin, or Vanguard/Powertech
Leveling as a duo, you will most likely steamroll through the content rather easily, so just pick a healer companion and maybe another damage companion.