Hand turning the motor
 

How can I do it, if possible? What should I disconnect?

I've never disconnected anything. ALWAYS!!!! Turn in the direction of the natural rotation, clockwise. Just put a socket on the crank pulley and turn.

Haven't done it on a 370Z, but, I agree with synolimit. Every other motor I've worked on was the same - put a socket with a LONG breaker on the crank bolt/nut and turn. Accessories won't add enough drag to make it worthwhile to remove the belt(s).

Edit: I have seen times where removing the radiator, alternator, &c made it a lot easier to get to the crank bolt and/or turn the engine, but, if you have enough clearance, you shouldn't need to remove anything.

Going from memory, since I'm not by my car. You might need to take off the overflow tank. That's about all I could think of that's kinda in the way.

Pull the skid plate and get it from underneath. From up top the fans will make it pretty tight.

Yeah, it would be a hell of a lot easier from underneath.

take out plugs to reduce compression causing more effort to turn? I've turned cranks by hand with ratchet and it was a b***h getting past what felt like the compression stroke on each cylinder. Of course my little chicken wings were straining like h*ll.

Definitely something to try if the engine is too difficult to turn over. Might get lucky and VVEL leaves the valves config'd so that effective compression isn't too high.

You shouldnt have an issue turning it by hand with a breaker bar. I can turn over a diesel engine by hand that runs a much higher compression than this car. You wont be able to turn it fast but she'll go.

Sweet! Thanks for all the replies guys!
I was going to diagnose, or try to diagnose my car issues. But it's going to the dealership soon enough