Douse in isopropyl alcohol, or brake cleaner. Wipe clean with a paper towel. If you're really worried, run some medium grit sandpaper over them before all of the above.
In my experience, no. The pad material is slightly porous and the fluid/grease/whatever soaks into it. You could try burning the contaminants out by putting them on a thick pan on a hob, which is the old garage bodge trick. I wouldn't though.
Douse in isopropyl alcohol, or brake cleaner. Wipe clean with a paper towel. If you're really worried, run some medium grit sandpaper over them before all of the above.