The "bolting down" question came out of too much time reading about vibration and isolation, but too little time reading it to understand it properly! There's going to be vibration, I need it to go somewhere but I certainly don't want it to go into the building structure.

As for the levelling question, I seem to recall they had made a horseshoe-shaped channel (ie the two mounting surfaces were connected to ensure the liquid level was identical in both) and filled it with some kind of liquid. I think it was for a lathe, if my old creaky memory doesn't fail me too badly. The need to potentially tweak and maintain levels as an ongoing concern completely escaped me. I was quite taken by the idea to be honest, it seemed like a very neat solution to a potentially awkward problem.