A: You would think so, but the feedback through the indicator system, if not resistored, will be sufficient to keep a car running. (there are multiple threads on this on various Hot Rod websites under Delco alternator conversion won't let my car shut off! Happened to me the first time too)
It would depend on how the car is wired. It's not an issue on my 63 Classic, nor the 75 Gremlin. I'll let you know if it's an issue in my 70 Hornet :-) That won't help anyone though as I wired it from scratch.