When it was rented at $700/month was that because of a negligent landlord and deferred maintenance?

@Raymond Hill every seller says that the knob & tube is inactive.I have no idea what percentage of time it's actually inactive, but for all intents and purposes, because sellers always say it's inactive, you can disregard what they say completely and know that if you see any knob & tube at all (usually in the basement or attic) you will have to specifically inspect that because there's a very non-negligible chance it will be active on at least some circuits in the building.I can't in good conscience say that you should close on a property with any active knob and tube, even if you plan to rewire the house, because I do think you have a significant amount of liability for the time between when you close, until the house is rewired.

Also in some situations, you can still be personally liable for gross negligence even if the corporation owns the property.

The above example only applies to situations where there wasn't gross negligence on your part.

One topic in the back of my mind is the landlord responsibility around issues of safety and negligence on the property.

He has negligible assets, and has one surviving, adult son.

It is very rare for this to occur for a purchaser. it is better not to complete such a form since you could potentially expose yourself to claims fraudulent or negligent missrepresentation. 

On other thing I've seen on several sights is how if you have multiple similar LLC's (like 10 LLC's for just 10 houses) the courts could tend to assume they are all 1 LLC type and if the suit proves true negligence a judge could decide against you and possibly pierce the veil.  

Tenant negligence, I would think not.

When comparing across thousands of households that is a negligible number.