Ceri JC

As SS says, plus in answer to question one: try using a 12 sided socket (sometimes even a slightly different sized one- eg the nearest imperial size) on the end if it is already so cheesed off as to be ruined. You'll still have to replace it, but it should be easy(ish) to get it off. I've even heard of people hammering 12 sided sockets onto an offending rounded nut to get if off, but that smacks of a real bodge (and of course there is scope for marking, or even knackering the socket, even if you protect the back end with a rag)!