205 is the width, R15 is the wheel diameter and the 55 or 60 is the profile height therefore the 60's will give a sightly more comfortable ride where as the 55's will ride slightly harder.
20560r15
Yes, that is a pretty good substitute.
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 you can
Yes, they can
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.
It is an acceptable substitute, but know that your speedometer will read 58.7 at a true 60 mph.
The rim size must match the tires unless you also change the rims to match the tires.