Yes. Your 205 tires will be 0.5 cm narrower and 0.085 cm greater overall diameter. This may cause a minor loss of traction, but in a pinch it'll work.
21560r15
Yes you can
No the rim and tire are too big.
You can find it on the side of the tire. Max Pressure.
205 is the width of your tire the 65 is an aspect ratio that determines how tall the tire is compared to the width
215 60 r15 is smaller, 215 being the width of the tyre, 60 being the height of the wall (% of the width) and r15 being the radius of the wheel
Maybe, depends if you have the clearance for the wider tire
Yes, you can.
What would cause a grinding noise after a tire is replaced and the brakes are not worn?
A bubble on a tire is caused by damage to the tire. It looks like a bump on the tire and should be replaced.
Definitely no.
As soon as practical. It will have a slow leak until it is replaced. Don't remove it! Your tire will go flat and you will be stuck.