USA...makes sense, since Mutable's in the EU and Intellijel is Canadian and subject to NAFTA tariff relaxations. Same difference, though...they're pretty much interchangeable.
Right...in fact, Maths is more complex, because you also have CV over 'rise' and 'fall' rates, allowing you to CV-shape the resulting output curves on the fly as part of your patch. Basically, it's a module that's derived from the classic Serge Dual Universal Slope Generator...and as such, you can use it as an envelope, complex function gen, LFO, or even an actual VCO at a pinch!
As for the 3hp Erica DSP...think carefully here: most of your signal paths tend to be mono, but the DSP has a mono in and stereo outs, meaning that not only is it an effects processor, it's also where you can generate a stereo signal to feed both channels of the Clouds. I jammed that in like that so that you could take a mono signal, stereoize it for the Clouds, then pass the Clouds on to the stereo channel of the Erica mixer. Thinking in signal chains like that is a real key to getting maximum function out of a build!