1.How difficult is it?
The most difficult part is deciphering the US Embassy website, IMHO. Really just a matter of the right paperwork, and it isn't that bad.
2.How much does it cost?
More expensive than when I did it, less than a year ago!
3.What ducks do you HAVE to have in a row?
Paperwork. Spouse having clear police record.
4. How long does it take?
It took us 3 months to get David's green card visa thingy.
5. What's the first step?
Asking these questions.