Engaged to an Austrian Au Pair - questions regarding marrage

My fiance was 25 months an Au Pair in the US and left without prejudice in August 09. She extended her H1B after the first 12 months. Currently she is back in Austria, and I have been visiting her and her family. Our question is, how do we now proceed with our wedding? We'd like to know what we'd need for the Engagement Visa, what issues might arise because of how much time she spent here, and typically how much time is involved for planning needs. If legal council is recommended, how much on average could that cost? Thank you.