Additionally, there’s always a risk that any pet-related damages could be hidden under furniture or otherwise concealed, potentially leaving us to cover the costs if the security deposit is fully depleted by other expenses (e.g., damages or unpaid rent).

I agree with Michael and JohnYou may get a small premium above appraised value for furniture and future bookings but that is about it unfortunately. 

How often are you replacing furniture and taking new photos?

The one cost will be getting the units furnished, but if you live in the area it isn't hard to source a bunch of decent 2nd hand furniture on Craigslist or FB market

This will likely be the smallest aspect of the company but seems like a sensible value add to the other aspects of the company, since we will have a storage unit with furniture/furnishings ready to go-Photographing properties for FSBO listings, or for clients we get for the furnishing/management side of the biz.

Let's say you spent a month on the initial preparation: cleaning, painting, shopping for furnishings, assembling IKEA furniture and so on.

Hopefully we get some better virtual furniture in listing pictures lol

The furniture guys will build and install mahogany counters and cabinets.  

The house had the utilities turned off for the 6 years, and was filled with the original 1 owner's furniture, clothes, appliances, car and ecn food in the frig (without elctric on for 6 years). 

Find a lawyer and issue a lease violation for other issues such as excessive noise and furniture removal.