Re: Choro guitar method?
+1 for investing in the White Books and reading the bass lines in there. Probably the single best thing that a classically-trained guitarist can do to get up the choro curve.
If your friend is in the Bay Area, then attending the Grupo Falso Baiano roda, even as an observer, will put him in touch with Brian Moran (7-string player).
He might also try to get in touch with Ron Galen. Ron comes from a similar background background (was a classically-trained guitarist who got the choro bug), teaches guitar for a living, and knows his choro inside-out.
Adult-onset Instrumentalist (or was that addled-onset?)