Yes it should.
Yes
I'm fairly sure that the 70-81 windshield is the same dimensions.
No, a Generation 2 (1992-1995) Taurus/Sable Windshield will NOT fit a Generation 3 (1996-1999) Ford Taurus/Sable.
Yes
Yes
Yes
Yes they are the same.
Need to know what part you are trying to fit.
Yes
Yes.
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.
sure it will fit in the engine bay, you will need to change the motor mounts and get the computer and wiring from the 5.7.