Yes It is located underdash on drivers side it is a 4*6 silver box with a wiring harness connected thru the fire wall.
No, under dash
how to change igntion lock
Look in the owners manual.
Yes
Change it
NO a grill from a 87 will not fit a 91. Only a grill from 88 , 89 or a 90 will fit. They don't even look the same.
No, the Crown Vic and Grand Marq used different styles of fenders
counterclockwise
Follow the + battery cable - should either be in the inner fender or on top of the starter
The 302 ( 5.0 L is fuel injected ) The 351 ( 5.8 L has a variable venturi carburetor )
I believe that is on a fuse panel under dash near drivers left knee
I would suggest going to an auto parts store like pep boys or such and get a Haynes or chilton manual. Not at all expensive and very helpful