I'd like to comment on the hole in the middle. I could list a lot of things not to do with it, but I think it'd be more beneficial to tell you what I know it is used for. It is a pad centering hole, most useful on rotary polishers so they don't get off ballance. You put a peg through the hole in the pad, and the backing plate also has a little impression in the center that the peg and hole match up to.
Does that make sense?
And think about how much pad you would have to compress to have the velcro "hook" side of the pad hit the car: quite a bit. I wouldn't be worried. At least I'm planning on not being worried. We'll see this spring!