Yes, you can
Yes, that's a reasonable swap.
It depends on if you have the clearance and the tires don't rub the inside of the fender when turning.>Al
21560r15
Yes, that is a pretty good substitute.
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.
You can substitute these tries if need be. But if you do this your car will be off balance.
no
Yes, you can substitute the 205/75-15 for the 215/70-15.
No, that is a very bad substitute. If you want to go with a 70 series tire go with a 195/70-15 which is a great substitute.
Yes you can
Yes, they can
Yes, they can