Tinkering with any of these settings also probably means you need to tinker with some of the (HIGH, LOW, MID), (elevation, volcanism, drainage, etc) initial requirements. Generally lowering them can eliminate any mass cancel you get -- though you might get some slightly less natural looking maps.
If you play around with the map painter, you can, assuming you don't mind spending a rather large quantity of time, figure out a way to produce dwarven civs in an area where there is rapidly fluctuating levels of volcanism -- specifically, you could go through and paint it out to go from 1 to 100, in a set fashion.
Then after generating, figure out which ones yeilded the layers you liked -- do this a couple times, with every thing always appearing in the embark screen, and you should also be able to figure out what the minimum volcanism for: Magma pool and Magma Pipes. Then, begin abusing that information by making a large plot of repeating features of your favorite layers, and magma.
As a note: Only one magma pipe will ever exist per 16x16 embark area squares. Likewise for pools.
Considering they only appear towards the upper end of the volcanism spectrum, in a regular world generation, this leaves a fairly small number of maps which a pool will appear next to say, flux.
My notes concerning underground pools and underground rivers, is that they will ONLY ever appear in a square which looks like a mountain on the overmap. (Embark, overmap, worldmap from left to right is how it appears in DF.)