Let's see here...

It reaches it's critical angle of attack around 18 degrees. Assuming you're heading straight down the runway (that's perfectly level) into a perfect headwind, you will touch down with an AOA of 18 degrees. The angle between the wings and the runway will be around 18 degrees... Then you're on the ground.

When the airplane is going straight up, the AOA is 0 because the angle between your wing and the oncoming air is 0. Have to remember what the angle of attack is... The angle at which the wing meets the oncoming air.

Spinning down means it is in a spin! Go back up and read what I said about spins. The wings are stalled and because of your rudder, aileron, and elevator unputs, it keeps it spinning in a certain direction. You've got to go try all this with your airplane. Seeing it happen will really help explain it all...It's tons of fun too.

Why does it become unstalled when you take the controls back to nuetral?

Remember I said the elevator is the angle of attack control? When you are holding pack pressure or forward pressure on the stick you are holding the angle of attack up. If you hold it back far enough for the spin, it will continue to stay at or past the critical angle of attack. When you let go of the controls (the AOA control) the AOA decreases and the wing comes out of a stall and flies again.