I believe you are correct in that more Protestants will leave a particular church to attend another just down the street which is more to their liking.
The fact that "local" (within 5 miles") Protestant churches outnumber Catholic churches about 15-1 doesn't have anything to do about it does it?
Yes, to question #1. And I speculate that the answer to question #2 is yes.
Question #3: quite possibly.