(As an umbrella question)How does the actual cost of capital compare?

You mention material defects, E&O, umbrella policy, etc.

As your assets grow you'll want to make sure you look into an umbrella policy but if this your first and biggest asset your liability coverage on the homeowners policy should be sufficient, just make sure you sit down with an agent to make sure the policy properly covers the property for how you plan to use it. 

I would absolutely suggest an umbrella liability policy.  

RE is under the financial industry umbrella in commerce.

I still haven't been convinced by anyone (through multiple discussions) that an LLC provides better protection than a personal liability umbrella policy.

Landlord insurance on each property and an umbrella policy will cover the issue if you get sued.

If there is a mortgage just have correct insurance and get an umbrella policy if your still worried.

Currently I have a personal umbrella.

You should also look into wrapping them up in an umbrella policy.