We have a T/T dolly and love it. We bought a HD model, white , electric brakes, with the 4' front stone guard, also at the time we also bought the diamond plate base to walk on, plus two ramps. The only thing I regret is we bought white instead of black. We had a toyota car, and I have a H/D full dresser so in order to get the car and toy anywhere this was our source to go to.
What kind of questions? The instructions that were provided were very good as to where to put the wheel rests, for the weight of the Front of the car, and weight of the bike so you can adjust the hitch weight, we kept the hitch weight at about 350 lps. We have taken it to Flordia many times running between 55 and 70 mph with no problems.
Good luck on your purchase