OY power, etc.

Knowing next to nothing about the mechanics of OY rotary at the C&TSRR, I'd like to ask: 1) Is the steam engine a piston type or turbine? 2) If a piston type, how many cylinders, and how are they arranged/connected to the shaft of the rotary unit? (I'd imagine that the rotary unit shaft is also the crankshaft for the pistons - is that right?)
Oh, and on a NNG topic (if I may) I think there have been recent posts here saying that the UP rotary is operated by the steam crew, so that must mean it's steam-powered, right? Wasn't it built much more recently than OY?
Many thanks for any info you can share!