Sure you could. Why wouldn't they let you? Would they have a specialized system installed you automatically prevent stages resembling non-Nintendo logos?

Again, sharing the level would be a different story. But I don't think most logos would make for good stages anyway.

Probably depends on how blatant it is. After all Nintendo can be sued for copyright infringement if the let a stage roam free who is looking to much (or named after) any game from their rivaling consoles. So of course they will delete such stages if there is too much of another Game's elements who don't belong to Nintendo in it, even if intended as an hommage or a Shout-out, but if the reference is kept small enough the stage might pass below the radar.

I was kidding too :O

I knew you were a warrior.