I am especially confused about the thermal expansion augments for power. Can anyone explain what base fuel energy is? And what's the best way to convert the steam I'm producing into power
The best option I've found is Steam Turbines from Big Reactors, or the ones from Reactorcraft if you've got that installed.
RC Steam Boilers don't run on steam, but merely produce it. They're what I produce steam in to run Turbines. I haven't done any testing with the MFR ones. I keep forgetting about them.