The primary residential structure on a collateral property burned down and upon updated inspection several low value non-residential buildings were identified (RCVs 2 x $1000, 2 x $1500, and one at $2000). The insurance company is indicating the minimum deductible is $1500, which means all but one building would effectively have no coverage since deductible is same as or more than the coverage itself. Are policies still required on those buildings? What about the building that essentially has only $500 coverage?

What are your values using ACV, not RCV on those non-residential non-OO structures. Chances are none will meet any minimums.

I will have to go back to banker/agent for ACV, is that now the required figure for calculating the "lowest of three"? Just recently returned from medical leave and am still trying to catch up on everything while I was out (insurance no longer being required on non-residential out buildings?)

Has been for a few years now, yes.

The only time you calculation using RCV is owner occupied residential property.