Yeah, Fallen, we kinda did that out of nowhere. Probably should have kept bumping the topic, or sent PMs. 

Well, you now my vote on the Planeswalker front. As for how/why they'd stay: I figured any Planeswalkers that we play would be freshly awakened, and perhaps they don't actually understand how to planeswalk yet, so they're stuck in the first place they accidentally pwed to, which happens to be Ravnica. 

I think three colors should be the max any one player can use, because otherwise everyone overlaps with everyone and it kind of undoes possibility for character conflict/interaction through differences. 

Well, I think the idea behind "lands" is that it's a place that a planeswalker has a connection to. So how about this slight change to that idea: Same deal, mana is easier to come by if it's plentiful where you happen to be. But, in addition to that, each character starts with, say, four "lands" that are near and dear to their hearts, and from which they can channel mana. And the kicker here is that characters who use more colors would have more difficulty casting their best and most complicated spells.