From fines for non-permitted work, no insurance coverage for unauthorized improvements, to injury/death liabilities for constructive knowledge of defects. 

Hopefully it doesn't.As for liability, the burden to prove that you're negligent in a situation after a third-party property damage or bodily injury claim is up to the suing party (your neighbor or their tenant). 

I don't need to tell them again that bouncing on a trampoline may result in injury or that cooking small animals in microwaves may result in death of the animal. 

But if the visitor’s injury is due to the tenant’s fault (i.e. tenant's failure to clear the slippery floor), then premises liability coverage would help but not personal liability, right?   

With this coverage, you are insuring against death, permanent injury, or scarring of a person (doesn't matter who) that occurs on your property.

Most likely the state where the property is located is where lawsuits would be brought if they are something for personal injury like a trip and fall or something of that nature because the “cause of action” arose in that state.

His charge is child endangerment resulting in injury.

As far as your neighbor goes, I'd be 'super busy' or acquire amnesia or a hand injury from here on.

I definitely believe most people should seriously think it through before painting brick, especially modern brick, because it's largely irreversible.

If your tenant does work for you, that's a lawsuit waiting to happen due to the possibility of the tenant injuring himself or causing injury to someone else.