If I were to get 2 2s liPo batteries would i need to change the brushed motors to brushless? Will the brushed motors heat up and decrease its life? How would I maintenance the motors?
No, the motors do not need to be changed from brushed to brushless when switching to twin 2S LiPo's.
The only additional thing to watch is for temperatures due to the extended run time.
If you decide to, you would also need to change the ESC.
Maintenance should happen just the same as you have been... and if you have not been, I suggest reading the manual about motor maintenance.
Whatever it is I just typed... could be wrong.
And on the e revo brushed how do u set the slipper clutch? I can't seem to find a way in.
there are a couple of screws to remove in order to get the cover off. That will expose the complete assembly....gear mesh and all. If you don't want to do that, I believe the cover has a hole in it specifically for the slipper clutch wrench to fit in so the clutch can be adjusted without removing the cover.