Aggie, you add a print the 1st time round, then replace your print on subsequent visits... well that's how I understood it.
I happened to be reading our local (to Australia! newsgroup and there was some discussion on 'travelling cameras' which is where a group of like minded individuals post a disposable camera around taking one shot at a time. Anyway, what I'm getting to is there was a link posted to a page describing it's journey and I was think we might be able to pinch a few ideas, mainly in that when anyone got the camera they wrote their thoughts/etc. I would probably say you shouldn't critique the pictures, just describe your reactions and maybe the reaction of anyone you show. I wouldn't make it mandatory but I could image a story or two would be interesting and keep interest while it gets to you (which might take a while!
and here's the site http://myweb.tiscali.co.uk/photoforum/ptc/ if you want a peek it. It's got the photos that have been taken too, which is worth a look.