Yeah the rubber part gets replaced.
Correct the spare tyre is the wheel+tyre as you can't just swap the tyre on your own. And yeah rotating is just moving wheel+tyre to a new position on the car so the tyre gets a different wear pattern which helps it last longer.
As someone who got into the closed beta a few days ago it is a fantastic motivator to get moving.
Absolutely love the artwork and the parts of the world I've seen so far.
Keep up the great work schamppu and team!