In reply to plummet:
Here's a good place to start with first aid kit contents, with some items to consider.
http://www.ukclimbing.com/articles/page.php?id=3593
MR guidelines for drugs is along the lines that you can give to over 12s without problems (allowing for allergies etc). I'd say giving topical antiseptic etc. so long as you check for allergies, to under 12s would be OK.
Extra to a standard first aid kit, (dressings, plasters, antiseptic etc) I carry some irripods, a pocket face mask and a pair of tick tweezers. My drugs for personal use include imodium, ibuprofen, and also aspirin and some glucose paste which I'd offer to other folk if the need arose.