Yes, they are.
No.
No, the brackets & everything are different since the body changed that year. The 73 has that wide strip between bumper & body so the curved sides longer to take up the gap. I think wheelbase also changed slightly. The 73/4 are the same.
A 1972 front bumper will not directly fit a 1973 Nova without modifications. While the two models share a similar design, the bumper mounting brackets and alignment may differ due to changes in the body structure and design. It's advisable to check compatibility or consider using the correct bumper for the specific model year for the best fit and appearance.
with the exception of the bumpers & bumper brackets they are identical
There are two;first one under front bumper; then one between hood & top of Grill.
I used brackets from 72 nova did a little cutting and they worked.
The bumpers from a 1970 Chevy Nova SS will not fit a 1973 Chevy Nova SS without modifications. While the two models share some similarities, the bumper designs and mounting points changed between these years. If you're considering a swap, you'll likely need to adjust the mounting hardware or brackets to achieve a proper fit. Always check compatibility with specific parts before making any modifications.
About 20 years.
Any other 1975-79 Nova front clips would work
Not quite, the 74 Nova had provisions for the shock absorbing front bumper in the frame horns which the 67 Camaro did not have.
Looking at the bumper, you will see raised, chrome, dome shaped, bumps. These are actually bolts, with a nut on the back sides. Then, it will just lift off.
There is a VIN located on the door post of the 1967 Chevy Nova. There is also one located under the left front fender that can be seen if the fender is removed.