Answers

Christofer, There is a lot written about your particular condition. What I would do would be to install a spray polyurethane insulation (closed cell insulation) into the attic ceiling and down to and including the eaves. this installed over a 1/4" plywood that would be "cleated" down at a minimum of 1" below the bottom of the roof sheathing, thus eliminating the "hot roof" situation. As far as moisture... if you understand that warm air rises and carries the moisture up (another reason i would use a closed cell product) then it makes sense to foam any walls or kneewalls as well. The venting on the top side would not be to eliminate any interior moisture, but to make your shingles last longer (keep them from overheating). Quite a few asphalt companies have disclaimers on warrantees because of this issue. You would need to check with your steel roof manufacturer how they respond to a hot roof application. 

Ok so you don't really want all that moisture collecting on your windows and or finished wall substrates in the attic. So an ERV/HRV or even the furnace fan run continuously would help distrubute or evacute the excess moisture if this is your main house furnace (air handler). FYI- change filters monthly in these systems to help mitigate possible mold issues. I recommend the 6" combustion air (bringing in dry outside air) code required in IRC. I am not sure if this furnace unit in your attic is the primary furnace (air handler) for the home. If so that would help distribute attic moisture to the lower parts of the home. If separate attic unit only, I'm not thinking it will ever distribute moist warm air to the lower level like you suggest.

Remember this... once you start changing the function of your home's ventilation/conditioned or unconditioning of a space you will be changing the whole dynamics of how the house used to function. Henceforth do your homework. All this said...I run my company business in the extreme temperature zone of Minnesota. Your local heating guys should have a better handle on providing a safe living environment for your family. Mold can be a serious issue.  

In MN. we have the same 3 day right to rescind. This is standardized form (written legibally) in type 10 bold letter type. My understanding, it is required to be given to the client if contract you sign is in the homeowners residense. Not if the contract is signed in the our company's office. We give it to our clients either way. The 1st day starts the day after you sign and is counted daily except for weekends and holidays. 

The real issue is... if you are having 2nd thoughts about being in contract with a particular contractor. I am thinking that I as a contractor, I would certainly need to know the issues, even if after "3 days right to rescind" has passed. I typically don't order product for any project until the time period has passed. If you want to get out of your contractoral obligations, there should not be any financial obligations from your part if contract is legally rescinded according to the form and in an appropriate time period. If after there may be some fees as your contractor may have spent time to proceed with your material and scheduling process for your project. 

Hope this helps.