Of course you can, but I highly recommend against it. The 215/70 tire will be 3.04% smaller in overall diameter and your speedometer will read 61.8 at a true 60 mph. Performance, handling, will also be adversely effected. If you wish to go to a 70 series tire then install a set of 235/70-15 tires which is acceptable and very close to the OEM size. Your speedometer will read 59.4 at a true 60 mph.
yes
no
Yes, that is a pretty good substitute.
Yes, they can
Yes, they can
Yes, you can
You can substitute these tries if need be. But if you do this your car will be off balance.
Normally. yes.
Yes, this is an excellent substitute.
Yes, that is a reasonable substitution.
Yes, you can
no there is too much height difference