I to made the switch from cars, and used to oval race them. I still have trouble flying in a clockwise pattern and constantly work on that.

As for time on the simulator,,,,,depends on the person I would say. Try to stick with planes on it that are the same as what you are planning to fly for real. Along with that choose an airfield on the sim that is close to what your real life situation will be. Runway orientation, trees and other obstacles. I have mine set up pretty close and it really helps. Last but not least always have a plan on whatyour flight will be, it helps out to know in your mind a flight plan.

The biggest difference I think are nerves and flying safe. No big deal to crash on the sim or make a mistake that might put property or spectators in jeopardy. I have been amazed at watching some guys with years and years of experience sweating it out at the field. That for me is the biggest difference.

Another thing depending on the plane with be wind and up/down drafts especially if you are using a lighter trainer aircraft.