Yes.
No. You'd have to buy an adapter
yes
yes
From the factory the nova had 14" rims but a 15" rim will fit with no problem.
The 1995 Pontiac Firebird can be fitted with 18x8-inch wheels granted they are designed for this application. A tire size that will work on these wheels are 275/40/18.
Will Pontiac Montana rims fit WHAT? Your question is not complete. What do you want to fit the Montana rims on?
NO!
Yes the do as long as the tire itself is a low profile tire meaning the tire on the rim isn't very thick
No
Yes it will fit, They are exactly the same body style
what Toyota vehicles will the 16x7jj rims fit