Yes, it worrks for both.
The covers will most likely come off. I moved a stove on a stone tile floor a couple of feet, and the covers came off.
You probably can, but if you get the felt wet, I wonder if it may get an oder in the future from getting damp.
It says 8 on the product info. Not sure if that's 8 of each or 4 sliders and 4 socks? I am assuming the latter.
As long as you want. If you are not fussy about them showing, you can just leave them there.
Use the carpeted covers for hard flooring. They work great!
need for heavy beds
4.75 inches in diameter, about a quarter to a half inch high.
The white plastic should not be in contact with the flooring tile. The rug covers need to be inserted over the white plastic discs, with the rug edge against the flooring.
I have only seen the combination package.