Depends if you want independant rear steering or not . You can get a Y harness with the litte reverser pot in it . That would give you 4ws all the time .
Or you can modify the tq3's 3rd channel for independant rear steer . As long as you have the forward only kit installed cause then you dont use the 3rd channel anymore . Thats what I have on my crawler . There is a good write-up about it on rccrawler..I can't get on the site for some reason. When I can I'll post a link for ya .
the rear is split off the front so they both turn at the same time. you can use the third channel to switch between turning the same way (crabing) and turning the opposite way ( sharp turns)
yes it would at high speed, its for more of a novelty. I will be using it on a slower rig, (not as slow as a crawler but same idea) so it will come in handy for tight areas.