Typical cosmetic (lifestyle) upgrades we do are better/more LED lighting, dimmers, flooring, paint, trim, solid wood door slabs in place of the hollow core etc.

(However, the software is geared towards smaller companies)(There are specialized softwares that larger companies use).Quickbooks can handle the accounting for a small business who does flips.In my opinion, you likely need to take a class on QuickBooks to properly and efficiently use the software.There are likely some schools nearby that will teach you quickbooks.The alternative is to out-source it to someone who is focused on the real estate accounting space.Best of luck.

Ensure all additions meet local building codes and have proper permits.In your specific case, converting the loft into a bedroom and adding a bathroom could be a smart move, potentially increasing your home's value and appeal to larger families.

Is it functioning properly?

Screen properly.

Another scenario could be that once the investor has the deed and I've been able to do proper due diligence on the property (value, title search, etc), I would consider lending against the property including renovation funding (per my terms).   

Brian I tried to connect but not sure my request went through properly on BP. 

And you have a vacant unit to do the "proper" plumbing repair.If you offer them a rent concession, my money is on them going back to that well each time there is a problem, asking for yet another abatement. 

Get 3 estimates, some times they will only  replace to the point of proper old sewer line only that can save money  BIG time   .They will add a clean out  next to the house one out farther where they stopped the new sewer line  replacement .As far as suing  any one on such a manner need to figure out what the legal  cost are plus what  percent chance of success then decide  of you want to roll the dice  unfortunately this type of scam happens a lot now a days .

Proper due diligence will reduce your risk, but it won’t eliminate it entirely.Personally, I like value-add opportunities because they build in equity from the start.