Done the camping with others before and if your like me, you get home late Sunday, unpack and then give all your a gear a thorough clean / fix up the following weekend. I have always found it a courtesy to help with the pack up / clean up after a trip, even if it meant the extend invites offered to come over for a couple of hours the following weekend e.g. Saturday morning to help with the last of the camping housekeeping issues.
With who brings what and preparation , sit down with the others and work out a list so everybody knows who is doing what, and what to bring, that way nothing slips through the cracks.
I would make sure things likes allergies, health/ medical issues are discussed with any new people to your camping group incase there is a problem.
Cheers
Campfire