Not likely
why not just use the correct part?
I have a 1969 Oldsmobile Cutlass supreme. My car has a 1968 front bumper, hood, and grill. Its mirror of your question but If a 68 can go on a 69 I wouldn't see why a 69 couldn't go on a 68.
yes
Yes, but the signal lights are the wrong shape.
does a 70 front bumper fit a 71 cutlass front bumper
Yes it will fit, the only different between these two cars is the design of the front and rear bumper, and they are fittable to each other.
No only 1970. 71 and 72 are interchangeable
yes
Nope.
The 455 will fit. The transmission might have a shorter tailshaft, though.
Yes
No
Depends on the year and bodystyle