or maybe have them on camera?

. - camera the sewer lines - get an electrician in there to check the wiring - appliance audit - how old, how much to replace, and any repairs done? 

Is the fencing with keypad entry, cameras?

Or install security cameras and report them to the police.

The prior owner is currently installing additional lighting and security cameras.

Occupancy is currently about 70% (one tenant, a photo/camera store, closed up shop because of the switch to digital photography). 

Yes, at this point in the cycle, sellers want big deposits, because they can get them, and because they want the buyers over a barrel in case the market turns against the seller before the deal closes.Obviously, putting up a bigger deposit, especially if it goes hard early (or immediately in some cases), raises your risk substantially.You definitely want to get a contractor or engineer in there, and absolutely someone with experience dealing with properties of this size.With a property that age and in that condition, you should also look into hiring someone to send fibre optic cameras down the water and sewer pipes.  

When selling a camera on e-bay for $50, a 1% fee isn't noticeable.  

Plumbing Lines and Septic Inspection - For $250 approx. you can have it inspected with a camera through the clean out.3.

(Obviously I will continue my due diligence after the walkthrough.)I plan to bring a notepad with plenty of paper, a strong flashlight, a good camera, and all the insight offered here.