Yes
Yes
Yes
will 24" fit my 87 caprice
Chevy didn't offer a 350 in an 86 Camaro, but if they did, it would theoretically work in an 87 Caprice.
1980 to 1990
No.... You need to change the whole back tail piece
Yes
An '85 Chevy Caprice Classic takes standard unleaded fuel (87 octane) unless if it is a Diesel engine. Higher octane is okay to use, however I am uncertain if it is okay to constantly use a higher octane.
1,8,4,3,6,5,7,2
if your caprice has a 305 or 350 already there shouldn't be a problem. otherwise new or custom motor mounts will be needed, also a tranny to match up to the 350 from the camaro
78-87 Monte Carlo is a G-Body GM car that is smaller than a 77-90 Caprice which is a B-Body GM car. The seats in a Monte Carlo will fit in a Caprice, but they may not look quite right. You will need to do bolt location modifications. I would not recommend trying to use a bench seat from a Monte in a Caprice. It is not wide enough.
85