No, didn't contact any congressmen.
I'd say it was a formal interview since my case was already approved and we didn't prepare anything at all. Most questions were like - which city were you born, names of parents, ever been to prison etc.
Main documents the officer asked for:
1. proof that we both live together - joint auto insurance or bank statements will do
2. both our passports and my wife's I-94
3. my employment certificate
4. wife's birth certificate - copy
Pardoner