building a pole shed

I have been thinking about building a pole shed for a few years, and I think next year is the time to start. can somone point out some things I need to research on this? this is a start of some of the issues I am looking at
40x40 shed in northern wisconsin as cheap as possible, I've been looking at recycling from other buildings for materials ( and cragslist free areas) use sonotube for forming pole footings fill to level 2 inches of ground insulation (does it have to be a specific insulation?) for frost to extend outwards 4 feet from floor of the shed how many inches of sand for burying tubing for future in-floor heat rafters or roof trusses? build myself or buy (building at zero cost is a plus) does NOT have to be a clear span, 20x80 would be the same sq ft, but I dont have the foot print for such
I am possibly considering builing it in 4 sections, 10x40 to help store additional shed materials and to make builing it easier.
I plan on hopefully pouring a floor for it in the late future, should I worry about the sand and radiant tubing now or then?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.