I am seeing 6-8% advertised caps on multi-family [before you make the adjustments for actual operating expenses, it is gross how negligent some pro-formas are]...

Maybe this is negligible for the peace of mind, but when evaluating the income potential of a property, it should be taken into account.Good luck, reach out should you need anything.

And if you are out there screwing people they'll probably find a way to reach through the entity to sue you for negligence or fraud personally.  

Obvious cameras deters most and will be the cheapest route.You can probably get by with locks on the doors, cameras and a camera at the gate that can activate when the gate is opened.If you have serious concerns, I suggest you speak to a security specialist, your attorney can tell you the degree of security needed to keep you from being negligent and keeping tenants reasonably protected. :)  

I do have a genuine interest in the property and I would be negligent if I failed to ask if you would consider leasing the property?

With rental property, the annual impact of the tax is negligible.  

My normal HVAC contractor (they also do insulation) says we can spray foam the roof line to seal in attic and then one big system, with only one zone will be fine....negligible difference between up and down temp.  

You should have had one come out, but if your realtor did not advise you to get an inspection done, then again it would be negligence on their part.

The question is, does a licensed Ohio realtor have a heightened legal duty to a tenant when acting as a landlord / property manager, or do the standard ordinary care duties for negligence and premises liability apply?

To do less would be irresponsible... foolish at best and negligent at worse!