Hi, no problem at all answering your questions.
1) Once I figured out how to get it off it was not too difficult, putting it back together again is another story.
2) I had a crystal shield on it and was using the case, so should not be an issue. I had to remove the shield though, but now have a different one on and no problems.
3) I think it adds 1/2 an inch to the thickness. The other problem with the belt clip is that the way it attaches to the back of the case does not seem overly secure to me. I've added a couple of pieces of scotch tape so that it cannot scoot accidentally, this in turn removes the ability to easily remove it.
4) If, after that you still want one, I got it from Amazon about a week ago.
For the record, I do like the case as I will use it because I won't be swapping cases, but if you only plan on using it part of the time I would suggest looking for a different case. I chose it because it would show off the iPhone(not mask the back of it) and because it had a belt clip -- these 2 things seemed like a hard thing to find as a combo.