Yes.
Yes
does a 99 camaro fornt end fit a 95 camaro
yes, even though they are different styles, (early 4th gen and newer 4th gen) you can swap front clip and make your 96 look like a 99 with no probs
no
Yes
The seats from a 99 tracker will not fit in a 96 because they are bigger.
yes they do
years from 89-99 the 95 3800 will fit those cars will even fit into the olds royale series same engine good luck!
don't think motor mounts will work - look for 92-99 3800
Yes
The 99 Buick Century 231 engine will fit into a 96 Chevy lumina with a little fabrication.
from 96 to 99 will all fit with no modifying.