Re: How would I apply music theory to the accordion?
A Cajun accordion needs no more theory than an ordinary harmonica/bluesharp.
A bluesharp has ten holes, and a Cajun accordion has ten buttons.
So you might just as well forget about the theory, listen, and try to play what you hear.
You're better off with one of the instruction videos of Dirk Powell or Big Nick.
Like Ron says, it's dance music, so the main thing is the rhythm and the groove.