No apology necessary. Good discussion of things a first time builder won't think of.
1) I'm on a rural electric coop. I don't know what my rate p/kw is. I have a transformer box and meter pedestal in the backyard. Cost me $1,250 to get those set. Then I buried wire to my shop and house. Short runs. I'll guess another $500.
2) I'm on a rural water district. Cost me $2,500 to get a meter set. Then I ran a buried pipe to my shop/house. Guessing another $500. Septic is a lagoon which I built. Guessing cost to plumb to it at $400.
3) No NG. Bought a 1000 gallon propane tank for 1,000. Guessing $300 for hookup. This past year I used 1050 gallon of propane at $2.15 p/gal.
4) Again, with my picky book keeper wife, if the outbuilding has electricity because the house was built, it counts.