Because efficiency is measured by how much heat you get compared to the electricity you put in, and heat pumps cheat by moving heat in from outside. So you get more heat than you could from the energy input.
I choose to believe in God; I don't have proof, but I like to believe. It makes life easier and in my case doesn't seem to have any ill effects. Even with everything we have learned through science, there still seems to be room for God. We don't seem to have any way to know what caused the universe to form, and I'd just as soon postulate an eternal God as an eternal universe even if it doesn't follow Occam's razor.
I also agree with 2-5, but don't agree that specialists always get further than generalists. I'm very much a generalist -- within the fairly broad realm of infrastructure architecture, that is -- and I think that's served me very well. To understand the whole thing, whatever it is, is very valuable.