You can use low voltage Zmesh under all of it. Though if you do use carpet, you'll want to lay some 1/8" leuon (cheap plywood) over the top of the Zmesh to protect it from the carpet removal in 10 years. It comes with a 25 year element warranty. It's made of bronze screen so it won't corrode and you can staple or nail through all you want without damaging it.
Here's a link. Be sure to scroll down the page to view the slides:
As for the 'no heat issue', radiant heat goes to cold. When we install it over a cold area, like a garage, we require a reflective barrier installed 1" down off the subfloor between the joists below. Then a plain fiberglass below that (R-19 if it will fit). This will create a great insulator and help to 'reflect' the heat that you would normally loose downward, back up.