Yes, she can come to the US via a K-1, marry, then leave. However, a K-1 is a single-entry visa. Once she leaves, it will likely become more difficult to get a B2 visa or to visit the US.
1. Unless her circumstances change, I wouldn't expect success.
2. Possible. But very expensive and time consuming way to visit once. The process will take about 18 months....maybe longer.
3. A spousal visa is for living in the US. It is not a tourist visa. There are residency requirements to consider.
4. Why? An attorney can change neither the law nor a consulate's decisions.