I am flying with 2 basic reactors, and energy restore is broken today. Ship stats say the rate is 15 (which is kind of not fair, should be 20, but this has been the case for a long time). However, the actual restore rate is 10, and this is new.
On reactors stacking: we actually went through multiple phases with this, going from "do not stack at all" (completely not fair) to "everything is just added together" (proved to be too over-powered) to the middle-ground we have now.
As for your actual enquery, yeah, I'm betting you are using ones with low durability.
Unable upgrade warehouse in SG2, or can't find right button.
I think it's under "Build" button.