Treek uses Aim, for 10-30s just focus on that. After that I think it is Aim + Power you start stacking, some crit, 40s more of that and Surge? sorta guessing, my highest right now is only level 30. I love Treek though!
With the Cantina rested exp some zones you seem to out level really fast to what quests are available. Speed levelers like that, but myself I do not. I haven't found any way around that other then skipping the next planet completely, and having my next character do that one and skip the other one I did do. Some I just level in Flashpoints, WZs, or space stuff. Good way to not get burned out on alts as well.
As far as achievements go, some of them seems like they are there more for people who have several alts, or those who want to go back at 55 that are bored (waiting in ques) to give them something to do!