A) Yes, you’re doing too much. Did you follow the newbie routine for a few months? How did you work up to all that clamping? That’s pretty much the most intense PE routine imaginable. Many penises couldn’t withstand that no matter how much training was done.
B) Hard to predict that kind of thing. Only experience in your own case will tell.
C) Whether any PE gains are truly permanent is controversial. You can find very lengthy discussions on the topic with a search.
D) I think that’s okay if it helps you to stay motivated (not bored) with your PEing. Most men do seem to find that working out 5 days a week, at least, is better than only every other day, once you’ve conditioned your penis sufficiently. If you require a whole day off every time to recover, you’re probably overdoing it.