Does anyone no the bolt pattern for a 1998 M3 coupe is it 5x120?

Yes, it is.

Yes, it's 5x120 but don't forget to check the offset before buying the wheels.

What should the offset be on say soem 18x8.5s or 18x8's Im new to wheels

I think 35- 45

k so 35 on the 8.5s and 40 on the 8's?

Even with 8.5" you can still go with 41 mm offset, it will depend on the width of the tires.