To answer part of your first post, when your loco crosses the gap seperating the reversing section with the other tracks, the reverser senses a short and immediately reverses the polarity of the reverse section matching the track you are coming from. Same would happen if the reverse section matches the track you are leaving, but at exit would reverse to match the track entered. This is done super fast and you won't see a blink in the headlamps, particularly if the reverser uses electronic relays. See Tony's Train Exchange for comparisons.
Yes, you will need a reverser for the turntable if one is not supplied. With power on the bridge rails, you need to reverse its polarity when making a turnaround to match the track you are going to enter. (If it is the one you came from, it will be now opposite.)
On your reversing section C : A short section is fine at longest loco length, but if you have lighted cars, it can try to reverse back in forth each time a car crosses a gap at either end and not know which way to go. Finally it will stall. With lighted pass cars, it is recommend to have the reversing track train length.
Something to think about: I have a hand built CMR turntable powered by a Dayton gear motor. Instead of fighting an aggravating, jogging, toggle switch, I installed a cheap loco decoder in the power feed to the bridge motor. Now I can hurry it over to the track I want and then slow it down to near nothing for perfect alignment. A plus is that any throttle can control it; just dial in its address.