So, here's an image that shows the layout of the jack (I had to look this up too). You solder right to the little posts/arms - I had a real fun time setting up my helping hands thingie to do them all at once, but it eventually worked out (yes, I own up to my crap tier soldering).
edit: the shorter post on the jack is right audio, btw - realized image doesn't really show that. long post is left, hook is ground.
As far as swapping out the board goes, I honestly haven't done it yet. I imagine as long as you get similar gauge wires (which Kitsch provides with the 1/4 kit, so I'm sure he at least has them) and 'extend' the wire by cutting, stripping, and re-soldering in a longer piece, you should be good.
Somebody who *actually* knows things should correct me.