Good news is its fully rented and generates enough cash to satisfy a 14% HML (give or take), that's pretty robust. 

Is looking online at sites like LoopNet sufficient? 

I tried to google but could only find vacantion-like sites with exorbitant prices.- Is there a kind of person who could help me with pre-sale improvements (roughly saying, to tell me what is worth replacing, improving, etc and what is not,1 to make the house more attractive for the buyer)?

You can check out sites like Zillow or Redfin to see what houses are selling for and what rental prices look like in your chosen market. 

There are some news stories about that street that I have no clue how to factor into an investment property value.

I wish a banner would call out theses dual types of listings but I would really rather them not allow for Airbnb listings on FF site and stay in there on lane as well. 

It's not perfect, but I like to read the reviews from residents on the site 

This is what I did for a cabin I built in Gatlinburg:  We took a few royalty-free photos of the area off of the internet, and submitted them to an art site online whereby they make a painting of the photo.  

At the end of the day vet these lead gen sites/companies on a short-term basis, then flip to something else if the leads are not working while having the right expectations.

Besides land, infrastructure/site work, and the building construction itself, am I missing any other major category of costs?