I'd say #1 isn't an Objective-C issue, but a Cocoa issue. Do not tarnish the wonderful language with the terrible framework. :)
I find that using a single XIB for a view controller at a time works the best for me, and maintains some semblance of MVC. I work on a relatively large app, with more screens than usual, and I never find it hard to figure out view controller transitions or anything like that.