Nope. the R15 and R16 are the size of the rim on the vehicle. they are not interchangable and must be the same.
No the rim and tire are too big.
the most nearest should be 275/65x15
The tire sidewall will list the max pressure. Check the owners manual or the driver door jamb sticker for the correct pressure for a vehicle
No, that would cause the speedometer to be off as there would be 1" difference in diameter. You can replace 215/55-16 with 235/50-16 which would both be 25.3" in diameter. You must keep the diameter as close as possible to the same 25.3" diameter as the OEM tire.
Maybe, depends if you have the clearance for the wider tire
What would cause a grinding noise after a tire is replaced and the brakes are not worn?
A bubble on a tire is caused by damage to the tire. It looks like a bump on the tire and should be replaced.
As soon as practical. It will have a slow leak until it is replaced. Don't remove it! Your tire will go flat and you will be stuck.
Definitely no.
Yes, that is reasonable.
Yes, you can but your speedometer will be off and the vehicle will handle differently and mileage will be effected, because the 215/75-15 tire is 1.4" larger in diameter. If you wish to go to a narrower tire then go with a 195/75-15 which will be only .2" larger in diameter and is close to the OEM size of 205/70-15. Why not just put the correct size back on the car?
This happened to me once - - have you checked the air pressure in the spare tire?