With regard to the coolong/heating coils, would you have two sets of coils, or one? If you only had one set, then you would probably have to have some sort of switching manifold for when you wanted to go from hot to cold. If you had to go from hot to cold quickly, it would present some serious problems. First off, you were talking about using high-pressure steam for the heating coils. The only kind of cooling agent I can think of would be fluid, so that would mean you would have to bleed the line EVERY time you changed. And if you had to go from really hot to really cold quickly, not only would you go through the bitch-ass line bleeding, switch over to what you need, then when you got ready and started up, the rapid temp change could cause some pretty bad warping. And if you had two sets of coils, it would cut out the hassle of bleeding the line every time, but it could still cause warping.
Do not go gentle into that good night. Rage, Rage, against the dying of the light. --Dylan Thomas