Everything you wanted to know about canoe design (but were afraid to ask)

I own a tandem canoe designed by John Winters and my seakayak was designed by John Winters.
The tandem canoe has less primary stability than I prefer, but very “seaworthy”. I have nothing negative to say about the manners of my seakayak. It was a pleasant boat to paddle.
This website contains a number of articles about canoe (and kayak) design that probably answer a of your questions. A few of the articles haver links to the figures, which is a pain. I ended up printing out everything so I have a hard copy.