Well, after reading about a sedo sale on another forum, it seems that buyers can back out even after agreeing to buy a name as long as its not the usual practice for the buyer (that came from a sedo rep), thus I would assume the same goes for the seller.
Sedo will provide you with all paper work to go after the buyer but they wont ban them from making more bogus offers, who has time to chase after these dead beats.
Sedo has to crack down on this, whatever happened to the whole binding thing... binding terms, when submitting an offer, it dont seem to apply.
I'm not sure about ? #1 myself.