For getting an ACW with better odds for the Confederacy, I've always thought that an establishment of the "Great Southern Empire" under American support would be a good start (basically, in 1855 a group of Dixie adventurers invaded Nicaragua and set themselves up as a puppet government, then were promptly kicked back to the south). Obviously, such endeavors wouldn't succeed, but if a few more happened, an "War of 1850" that saw British and possibly French troops on American soil in response to American "Imperialism" would be plausible. From there, a European focus on hitting American industrial centers (e.g. the North) would even the odds in a future ACW.
Returning to your ideas, though, I don't think that an independent California would do the trick - simply too little fighting occurred there, and their troops aren't enough to tip the balance. Your idea of Canada joining the union and thus more OTL states seceding is also a bit far-fetched, IMHO, but with butterflies its certainly possible. OTL, no one really wanted to secede from the midwest after Bleeding Kansas drew such a dividing line. Really, your best bet would be to avoid Bleeding Kansas altogether (of course, your initial proposal would do just that). With more holdings in Canada, the US will be far more influenced by the French, probably to the point that, should the French Revolution happen more or less as OTL, you'll see quite a bit of immigration to the US once the reign of terror gets going. What you really need in the Midwest to go with the South if you want to even the odds, which means you'll need a reason for the breadbasket states to join the King Cotton states, with whom they have a loose relationship, instead of the Northern industrial states, upon whom their economy was largely dependent. Having a "French-Yankee" North+Canada look increasingly down upon a German-Irish-Italian Midwest, an independent breadbasket from Canada that can compete with the Midwest, some sort of "Bleeding Ohio" fight over cultural differences, and a bigger slave presence in the Midwest (all of which are possible given your initial POD) should do the trick. I hope this helps!