Stan did play a 12-er on some songs, others a 6-er. He used DADGAD sometimes, other times he'd use DADGBE (think 'The Jeannie C) or EADGBE (e.g. 'The Field Behind The Plow"). He wasn't tied to a particular instrument or tuning.

Stan did mostly play with the band (Garnet, Paul Mills, David Woodhead, Grit Laskin et al), but played solo gigs too - I have a private recording that was given to me of his appearance solo at The Bermuda Folk-Club, including his brilliant slap-down of some gobby heckler. Magnificent performance, and some magnificent singing back from the audience too.

For Stan's songs I try to use a similar pick to the one that sounds like the 'main' thread in the accompaniment - it's usually pretty easy to hear, not always easy to play.