dude i also have sympathy it does hurt like hell. On the plus side once the area heals the skin there kinda hardens and the nerves are dulled so after awhile you do stop getting it on your feet. As for the knees plenty o guys wear knee pads, im not talking big skater boy things just like a bandage. It does hurt real bad, but the only thing you can do and mean it in the nicest way possible is to man up and get on with it.
Oh and dont wear wrestling shoes cos then you'll be, 'that guy who wears wrestling shoes to BJJ.'.............no one wants to be THAT guy.