Okay...I'm not a NE Ohion, just a lowly southern Indiana-ian, but I'm still gonna' throw my 2 cents in...
I'm guessing you guys get colder weather, and probably more snow than we do. I'll tell you that MY girls would not go out on really cold days (well...they'd go out for a few minutes, shiver a bit, and then head back in for an hour...lol), and they wouldn't go out in the snow at all unless I shoveled an area for them and threw down some straw. That gets old pretty quickly. But THAT'S exactly why you need to build a roomy coop. Summer time is not a big issue. It's winter time that's the killer. A roomy coop makes for easier clean-up too. Imagine a family of 5 living in a 1000 sq. ft. home vs. the same family in a 2000 sq. foot home. Besides being able to tolerate one another better (lol), you don't notice it getting dirty and cluttered as quickly.
1) The 4 sq. feet for standard chicken "guideline" is really a minimum for healthy/happy birds, IMO. Even better if a person can give them MORE... and plan for the bigger amount of chickens you want. If you don't want to go that big, reduce the number of chickens you "adopt."
2) Does the COOP need to be elevated??? No. Mine (and many others') sits on blocks leveled on gravel. I think many small coops are elevated to use the space underneath for run space. But larger coops generally aren't elevated, at least that I've noticed.
3) I'd say one for every 4 chickens you end up with...maybe an extra thrown in...
4) I LOVE having insulation. It puts my mind at ease when the temps drop down into the single digits in winter. I went with the pink fluffy fiberglass stuff, but many go with the foam board insulation. You'll never say "Dang. I should NOT have insulated!!" But you do have to cover the insulation of course (or you may very well be saying what I just said you wouldn't...lol...'cause they'll eat it)
5) Some love shingles, some love metal...ours is metal over plywood (and insulated ceiling of course)
6) The sweeter heater looks great to me, although I don't own one. If you're considering a heat source, it makes even more sense to insulate to me...else you'll practically be trying to heat the outdoors.... I use a heat lamp (hung on chains...not clipped) w/bulbs as low as 75W (although there were a few nights I stuck a 250 in there...but my goal was to keep it above freezing in my coop). Many don't add a heat source unless it drops below zero...depends on your breeds, your birds ages, your outlook/goals for your chickens.
Oh yeah... and if they are totally going to be free ranging, then will they even need a run??? Or were they going to be free ranging part-time and in the run part time???