If you've got an ablative paint on your boat, don't scrub it with a scotchbrite pad... you'll take a lot of the paint off unnecessarily doing that.
Completely dependant on the degree of fouling. Ablatives aren't special, they get just as dirty as anything else and a dirty ablative bottom isn't going to be cleaned with a piece of carpet any better than an epoxy bottom would. But ablatives are
soft and you do need to take care with them, regardless of what you clean them with.