1. Some do, some don't... Check the features by trim. (I think Premier and Empower do? Evolve doesn't.)
2. Neither? Both? They're alloy wheels with multiple inserts. The inserts probably help a little with aerodynamics, but the wheels also look good without them.
3. Yes. Not only is it controllable, you must control it. It's not automatic.
4. On FWD models there's a floor with storage above where the spare would go that most people don't remove. Under that is a foam insert. Remove the foam insert, and there's a spot for a limited-service spare. Nissan doesn't offer one, and doesn't say what size would fit, so it'll take someone some experimentation to figure this out. NOTE: This might not be true on the AWD version. No one has seen what's under the floor on that one yet, and it's possible that space isn't present on that version. Also, on models with the premium sound system, the sub may be in that space.