Topline does not make spacers that are 1" wide. You're going to have to go to ebay or a porsche place, like
www.pelicanparts.com (good people).
Wheel bolts were not a problem for me because I converted to studs and lug nuts, which I think is a must for such a large spacer. Topline may be able to help you there, and a bolt-on spacer will have it's own nuts to secure to the drum's studs.
Slip-on spacers are cheaper because they're basically just one big chunk of aluminum/steel, but they need super-long studs to slip on to and for the wheel to attatch to also, which boosts up the price, thus negating the cheaper price. I run bolt-on spacers, FYI.
You could also convert your trailing arms to aluminum 944 ones, but spacers ar so much easier and faster and will be just fine on the street, as long as you use proper torque setting on all your bolts and nuts and all that.
I hope i've helped.