- Gravel for drainage preferably with drian pipe, then 16" gravel as industry standard in Penna. Rebar + thickened edge. No problem. 
- OSE - we did a 64*60 slab for the workshop, rebar + 16' control joints - no cracking or heave at all so far. I still don't understand what frost heave is, never seen it in any of our structures with the shallow insulated footers. All you need to do is observe that when you put insulation down - 2" thick - a little below soil line - it never freezes below it in diwn to -10F winters.