From the amount of use and type of terrain your describing I would say you could probably easily expect 2-3 years from my experience with danners, as long as you properly care for them. Keep them oiled and dont put them away for the year caked in mud
Not sure there is a “truly waterproof” leather boot, that being said Danner is an affordable option to get into, tho not the quality of the higher end boots
Guiding for ten years I would say the average shot is 200-250 yards. Usually if you don’t bust them when you first see them you can get to that distance fairly easy.