No, the 1957 Chevy didn't come with seat belts.
Not if they did not come from the factory with seat belts. If they came form the factory with seat belts you are required to wear them.
No type of glue should be used on seat belts.
Seat belts, yes.
I believe it was the first year of seat belts being standard equipment on the Thunderbird.
Yes, the 68 VW came with seat belts for both front and back sets. The front seats for the Beetle were 3 point retractable seat belts and lap belts in the rear.
It is probable that no one knows this answer. Auto seat belts came into use well after seat belts had been in common usage in aircraft for decades and decades!
Yes
Yes
if the car didn't come with seat belts on those seats from factory you don't need them. but i'd say put seat belts in anyway you can never be to safe.
because it is fun
Yes.