How's it going, I am a dentist working in Boston, MA with a decent amount of book knowledge in REI.

Exterior was the wavy pattern fiber cement siding and was easy to match.  

The Unilin 2g locking system is one of the most efficient ones on the market.I 100% agree the the subfloor/ underlayment/ substrate being attached to as well as how  it was attached to the builder floor(naturally we're not talking cement) is usually the problem in a failed installation. 

Another we looked at was physically in two pieces, a left house side and a right house side with a crack 1-3 inches wide through the cement floor front to back. 

The backyard was mostly broken cement and terrible metal fencing.

When I see rust eating at welds like this I wonder how much of the problem comes from the management company (Rust never sleeps).A maintenance tech scheduled for some time with a wire brush and some Rustoleum could have saved this expensive cement tread stairway.Now it a welder (if it's salvageable) and the Rustolem, plus the cost to construct that ugly unpainted wood bridging system, and tear it down.And despite all of the drama that's going on, Mrs Kitty still has her favorite spot in the shade next to her food and water--a natural foe to garbage rats.

I'd go with stained or polished cement With stained they can usually add and 1/8th" or so overlay (they then stain the overlay) so any preexisting stains or anything is fine Polished cement (in my experience) is the opposite - they essentially remove 1/16-1/8" of existing cement, so surface stains will be removed but anything that has really soaked through may still remain to an extent Yes water will get trapped between the LVP and existing cement/water barrier - for this reason I would not do LVP Could go tile - but why would you when you can stain/polish it for cheaper and not worry about cracked tiles years from now when you can't get a replacement 

B buy a building with your credit, get a mixed use approved. don't improve 7000 sq ft as a tenant. all the rich guys are owning real estate. negotiate with yourself market rent and multiple tenants. occupy less than 25%. look at land. don't do this. 7300 sq ft is crazy to build out for a dental practice. get a few other dentists to split the cost with you and do a sale leaseback, you can probably sell the building and roll the business up to a private reit attach real estate to it. 

This ^^^ Or just build the little wall and stand it up in place...attach to ceiling and floor, apply vapor barrier and then cement board.

What you are probably smelling is the cement.