You would actually be using the piece hardening instructions, unless you're giving instructions to a larger heat treater or you have a very large heat treating furnace and many knives that you haven't told anyone about. The pdf I tried to put on rapidshare has a nice chart for holding time at austenitizing temperature. I'll e-mail it to you. The longer time required by what you're looking at is because you're looking at the instructions for the batch hardening. The hold times for piece hardening on the Sandvik website look fine though.
You can use just about any plates as long as they are thick enough.
You don't need to cool it in the fridge first. Around room temperature is fine.