Yes
Yes. Your speedometer will be slightly off, but only by .95 MPH at 55 MPH and 1.12 MPH at 65 MPH.
Yes, you can
No, the difference is way too much and it would very likely rub the body while turning.
yes, there not as wide as the 65's you have on there now-- the smaller the number, the wider the tire is
Maybe, if there is clearance for the wider tire.
215/75-15 225/70-15 235/65-15 245/60-15 265/50-15 Check for clearance issues on the 65, 60, & 50 series tires.
Switching from 255/70-16 to 265/70-16 will cause your speedometer to show 58.9 mph at a true 60 mph or a difference of 1.1 mph. A better switch would be from 255/70-16 to 265/65-16. Your speedometer will be off .9 mph too slow.
From $65 to $265 depending on the quality battery you buy.
Can you? Yes you can. Should you? No, you should not because the 65 series tire is 4.84% (1.47") smaller in overall diameter than the 70 series tire. You should never go over or under 3% difference. If you wish to go to a 65 series tire then you need to install 265/65-17 tires that are only 0.19% (.06") larger. That size will be an excellent fit. A 255/65-17 will also work well but not quite as well as a 265/65-17. A 235/65-17 will not work well and you should not install that size. Know that the 265 may rub the fender liner when you turn sharply so check that.
If that vehicle has all wheel drive all 4 tires need to be the same size.
No you can not. say for example 265 70 R16 the height of the tire from the rim to outside of tire is 70% of the 265. you can use a calculator to find what size of tire you can use other wise your speedometer will be out