1. Depends on the friend or relative in question. Would find it hard to say no to close family members. Rob's parents have their own motorhome which they will not lend to anyone so don't think his family would ask as a precedent has been set. Claire's brother's response to the news we were getting a caravan was "Oh good, we'll be able to borrow it!". He hasn't asked since we got it though so we're not pushing it.
2. Same as above really but would probably have to lend out our car too to tow which we actually feel more concerned about than lending out the caravan.
We have friends who frequently borrow her parents caravan. Her Dad tows it to wherever they want to holiday, comes home then goes back to collect it at the end of their stay! They've got it made.