Szabo was a University of Washington compsci undergrad, and then an engineer at Digicash and a certificate authority company (forgot which). Then he went to law school. So he definitely knows how to code, but it's unclear if he's current with it, or perhaps rusty from not doing daily for a long time.

I suspect Hal Finney was behind the Satoshi handle on the original mailing list, and I wouldn't be surprised if he enlisted Szabo to help him write the paper since Szabo was also on that list, is a good writer, and Szabo's Bit Gold concept is pretty close to Bitcoin. But it's most likely Hal who invented Bitcoin's architecture and coded it up.

https://en.wikipedia.org/wiki/Nick_Szabo