A livestock tank heater shouldn't cost a lot.. i have one for the horses and i know there are floating types... it runs for months end in winter i see no adverse effects on my hydro bill, they are thermostatically controlled.
Not handy i don't really shovel anything, other than the duck barns front porch and that is for my benefit and being able to open the door! lol as for ponds i chip ice out of them till they start to re-freeze immediately and then just cease for the season.. they do sneak into the horse trough...
Nice set-up! love your wooded surroundings... we have stalls set up in our main house to keep our drakes although i have one hen who flies in with a different one now & again lol Love the second house.. i think i'd like something like that for the mallards.
That's why mine are housed overnight not penned, while i am certain some can create predator proof runs/pens we couldn't(too costly) so we opted for a building instead.