Hi Steve,
7d - the S at the end is from "president", and that goes around/'concealing' "legal cash"
I'm as baffled as you by the 4th S in 13d.
For my part, I can't really see how the answer to 5d means either "believes in" or "counterfeits".
Also, while the answer to 20a is clear. I'm not sure how it's derived from "bug... bear"?