Yes, they are
No. There is 4.34% difference in the diameter which is too much. Your speedometer will be off 3 mph. 195/70-15 would be a better swap for 215/60-15 tires. It will only be 2.3% off and the speedometer will be off only 1.4 mph.
Yes, you can substitute the 205/75-15 for the 215/70-15.
No it will not. If I understand your question correctly, the tire you are looking at is 15" in diameter and your rim is 16" in diameter. You need to buy tires that are made for your diameter wheel, 16".
Can a 225/60R 16 tire replace a 235/70R 16 tire.
Ideally you should have four tires on the car that match. With that being said you can certainly replace your 65r tires with 70r tires. The 70 refers to the width of the tire and a 70 is slightly narrower than a 65. The lower the number the wider the tire. I would not put 1 65 width tire on one side and a 70 width on the other side of the car, they will wear unevenly.
Technically, yes. Your speedo will be way off however. Those tires will be a lot taller than what the computer is set up for. It will show that you are going much slower than you actually are.
215 x 70R 15
175/70r/13
NO, the rim size is different.
The original tires are 225/70R 16
Yes, that is a common size for that car.
Depends on what size you want. If you want bigger tires on the back than on the front, you can run a 235 or 245 60R 14 on the rear and a 205 or 215 60/70R 14 on the front. Of course this depends on the off set of the rims and if the car has been lowered. This answer is under the assumption that the car is stock factory height and the stock or normal off sets.