I rebuilt mine last night. New SPI pistons with a used head and jug. You're supposed to torque the head first, then the cylinder. It's a bitch though. The inside/rear cylinder bolts are almost impossible to get to. I pretty much just made them tight as there was no way of getting a torque wrench on them. I used the single layer gasket. It's what my dealer sold me and I didn't know about the double until I pulled my jugs off. The thing runs fine with 135 psi compression. We'll see how it holds up.
Yes, I put the raised portion up. I knew I had read it somewhere, but couldn't find it when we were putting it together. I'm running 87 in mine. I don't see any need for higher octane. The dealer never mentioned the difference in gaskets.