No, this is a horrible swap. The 65 series tire will be 9.79% smaller in overall diameter which is way too much of a difference. Your speedometer will read 66.5 at a true 60 mph. Your handling, ride, and performance will be adversely effected. If you wish to go to a 65 series tire then go with a 245/65-15 which is almost exactly the same overall diameter as the 75 series tire. Just make sure you do not have clearance issues when turning. A 235/70-15 is also a good swap and is what I would recommend.
Yes, you can
Yes, if you mount as a pair. Both tires on axle must be the same
Possibly, check they don't rub anywhere while steering.
NO, rim size is incorrect.
195/70-16 or 215/65-16 are both acceptable substitutes.
Yes, they can
Yes, you can
Yes, that is a pretty good substitute.
Normally. yes.
You can substitute these tries if need be. But if you do this your car will be off balance.
no there is too much height difference
Sure, if you change all four; the difference is about a quarter of an inch in diamater.