Check your RPO codes. If it has K60 then you have a 100 amp alternator.
215/60r16 if your stock rims are 16"
323
barbecue gold was one color
they stock 307 engine code "9" had 170 hp for 1987
check your specification decal on the drivers door if it's still on the car.
check your drivers door specification decal fotr the tire size.
It is best to leave this up to proffesionals who specialize in remanufacturing alternators. Contact your local autoparts store, they will be able to help you out, & they probably have a remanufatured alternator in stock at a competitive price.
4x10 though if you order 6x9s from crutchfield they send you adapters to fit the rear deck
Try www.nada.com
The GM 4T60-E is the stock transmission on the 95 Cutlass Supreme.
Considering it doesn't sound like it is stock it's impossible to tell how much HP it has without knowing exactly what has been done to it.
stock size is P235 60 16