75 is a really long course. Ours are generally in the 50 sec timeframe, so you can memorize the course and really focus on hitting your marks from memory. If you are running against E36 M3's (with a little suspension work), you are in bad car class. I'm in a class with slightly mod'd E36 M3's, and I'm often slower. The traction control is hurting you some, your tires are hurting you some, not being able to memorize the entire course and figure out which corners to "sacrifice" in order to faster later on, is hurting you, no LSD is hurting you, and driver experience is hurting you. The good thing is most of that can be fixed with practice and a comfort level with the cars characteristics. Autox generally is "slow". In 90+% of the autox events I've run (BMW CCA & SCCA) I haven't needed to go into a gear higher than 2nd.
And yes, you should drive on the street and track with BOTH hands.
You have much better control and feel with both hands and for tight turns you may need to shuffle steer, but short of shifting both hands should always be on the wheel.
Good luck withy our development!!