Gaurantor Membership i believe would need to be overseen, Normal members however would probably not need to go through the same process as it isn't a legally binding position. I suppose thats something the first board needs to decide upon.
True. I tend to forget about supporting membership, since it's a fairly meaningless thing - it just means you're a regular donor and get an email every so often. I would hope that most people become guarantor members, otherwise they're not really involved (I think anyone representing the chapter at official chapter activities ought to be a full member of the charity - they're the people best placed to be voting at AGMs, etc).