NO, this is an unacceptable swap. The 205/70 tire will be 4.34% too large in overall diameter. Your speedometer will read 57.3 at a true 60 mph. Ride, handling, performance, and braking will be adversely effected. You should not move to a 70 series tire because you will have to install size 185/70-15 to be an acceptable swap which will effect all aspects of the tire. You can go to a 65 series tire in size 195/65-15 which is a good swap. My advice it to stick with the OEM size which the engineers who designed your car have determined to be the optimum size.
Yes, you can.
It depends on if you have the clearance and the tires don't rub the inside of the fender when turning.>Al
21560r15
As long as all 4 match, the height difference between 65 and 70 should not cause a problem on most vehicles.
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.
Yes, they can
Yes, you can
Yes, they can