It is ok to "overpay" based on your standards if the location litterly can't be beat.

Actually Paul the state is the one with the energy building codes, in particular CA Title 24 2019 standards that just went into effect January 1.

Work must comply with social distancing standards where possible."

If that agreement is violated then you will have to sue in a standard civil action.

Yes, Business Income is a coverage that is almost always automatically included in a small business policy if Tenants or customers of any business stop paying, that is not an insurable claim on a standard policy.There are some products in the REI space that can cover this, like Rent Rescue, but not sure if their policy would respond to this.

You may need a more powerful unit that exhaust closer to 100 cfm versus the standard 50 cfm. 

Some of them even mentioned that they might even raise rates to as high as 14% (before, most of them did the standard 12%) in these troubled times which to me doesn't make sense at all.

Now that that is accomplished, we’d like to know what other seasoned hosts use as standard practice that isn’t too restrictive in nature and doesn’t inhibit  steady bookings... but reduces risk to the property.  

Before you can make your calculations, you should research your market to discover which ones are standard to pay for.

It's completely standard for things to come up on an inspection with turnkeys.