I fail to see the problem. Could you elaborate?
Sure. If by "membership structure" you mean several hundred "members", as we would expect, will we all be "guarantor members" of the company (and then the charity later)?
It will be up to the individual members under the current plan. If people want the legal liability (all £1 of it!) in exchange for a vote, they become a guarantor member, if not they just become a supporting member (which is how the last incarnation intended it to be, I believe).
Alison mentioned something about it being legally questionable to charge for guarantor membership, although my personal research suggests she may possibly have been mistaken (it's not at all clear, I think someone will have to actually enquire with the charities commission about that one). If that is the case, then guarantor membership and supporting membership will be independent of eachother, if not then guarantor membership will probably be a subset of supporting membership (we'll need to discuss that in detail at some point - there will probably need to be room for exceptions since some people may be so involved it's stupid for them not to have a vote, but not be able to afford membership).