not sure how much this helps, but I currently live & work at a barn that has *generally* the same sort of set up as you described. We have stalls inside the arena, covered & enclosed on all sides with no heat. Tack barn is a separate building. However, we do have lots of turnout space (I know, there are some differences)
Anyway, up here in Alberta, we charge $175 for outdoor and $275 for indoor.
The average is $350 for outdoor and $500 for indoor (obviously some barns are higher/lower)
Dust is a problem, as it's winter we can't water the arena, so we open the large doors whenever possible to get lots of fresh air moving through. (luckily we don't have many active riders, or this problem would be much worse).
And the cold, well, you learn to live with it. At it's coldest, our barn drops to -15c (outside temps around -30c). I've found that unheated & uninsulated barns lose heat quickly and hold in the cold well (obviously the opposite of what you'd want). Layer up! I've worn up to 5 layers to work. Sure, I couldn't really bend my knees well, but I wasn't freezing lol
And as others have said, expect and assume that everything will be costly. I only hear generally what my barn owner has for bills, and with working full time and having 10-11 boarders, she REALLY struggles.
Best of luck!
" If the entire world was one big machine, I couldn't be an extra part. I had to be here for some reason." ~ Hugo Cabret