I'm not an expert here, in fact I've been seeking advice myself in my situation.
Like what other people say, the key to this is the Annulment process, what it entails in terms of money, and time frame, and also someone quite rightly pointed out to me, the very very important thing is getting the right lawyer, but it seems you may have this sorted
Regarding getting married, I think you have two avenues. Getting married over there, then applying for spouse visa...or getting married here. Getting married here, would require her to get a "fiancee visa" which would be for six months, in which time you'd be expected to get married here. Then once married here you'll apply for a spouse visa, which I think is issued for a "probationary period" of 24 or 27 months, or there abouts.
Whatever path you go down, remember to keep all correspondance, all evidence of contact between you both, in order to help support your application in the future.
Good luck !!!
