Us masters spent some time over at DD sorting out the masters rules for GS with some of the guys from Russia. I think if you substitute 15lb clubell for 24kg kettlebell, and 25lb CB for 32kg KB, you could pretty much just graft them right in.
1) Masters compete with the 15lb CB. Masters OCS "records" would be recorded with regards to the 15lb CB. Ofcourse, a master could always choose to compete in the open class with 25lbs, but that would not be scored in the master's division. A master who chooses the 25s can't win the masters division and is simply competeing in the open.
2) In regerds to the ranking chart a master recieves no brakes or advantage. Masters are ranked by weight division like everyone. So if you compete as a master with the 15s you can "only" go up to CMS ranking. There is no MS with the 15s. If a master seeks MS status he has to jump to the 25s.
of course were not bound in any way to this - and in a completely selfish and self serving way, I'd like to be able to get MS with 15s - but that's the GS structure for what it's worth.