[Varyon]

I think those are probably mostly close enough, with the possible exception of the vacuum energy power plant. Antimatter, fusion, and total conversion are, unless I'm mistaken, basically all really advanced heat engines (much as modern nuclear power plants are). A vacuum energy plant would, presumably, only produce heat as waste, not as an intrinsic part of its general operation, so I'd expect it to have a smaller signature, if any. I could see vacuum energy plants, depending on fluff, being anywhere from +3 (no difference from the systems it powers) to the +7 of total conversion, or possibly even higher; personally I'd peg it at +4 or so.

For the solar mirror systems, I'd probably have those close to lightsails - just like the latter, solar mirrors are extremely reflective. Now, typically the brightest light source will be directed into the ship's bowels, so it probably won't be quite as bright as a lightsail. +6, perhaps? Note that makes the signature of the system it powers academic, as the mirror itself is far easier to detect.