While I haven't done new construction as an investor, I've been involved with them on the design and construction side. $15-$20,000 seems like a very small profit on a $500,000 house.

We are experienced and have never involved anyone in our projects and have never used a loan outside of a conventional mortgage.

At minimum, I am looking for the name of the deceased, a name of the personal rep/heir, and a name/contact for the attorney involved. 

I recommend you read "Long-Distance Real Estate Investing" by David Greene.

The property manager should be involved before you buy any property to give input on due diligence, how to increase income and reduce expenses, and to make repairs or improvements to maximize occupancy.Excellent property management is critical to your success before, during, and when planning to sell or refinance.To your success!

Build a solid foundation before taking a step up - each and every step of the way.There’s a way to scale recklessly and there is a way to scale safely.When OPM is involved safe is way better than reckless.Despite a life long career in RE, I scaled as followsBought a few duplexes for my own accountBought a fourplex for my own accountBought 12 units as a JV with some friendsSyndicated 43 unitsSyndicated 30 unitsBought another 12 units as a JVSyndicated 281 unitsThis was over a 3 or 4 year period.and so forth - now I am GP in close to 1000 units with $125M AUM.Even with all that, my sweet spot is 30 to 50 unit properties - they work best for my partners and I and more importantly our investors. 

Whether you're interested in residential properties, commercial spaces, or real estate investment trusts (REITs), there are various strategies and approaches to consider.Real estate investing also involves understanding market trends, economic indicators, and demographic shifts.

In this era of increased rates, obtaining properties that will produce a good return are harder to find and often involve quite a bit of work.  

As far as the sale of a property with a mortgage on it, that all gets sorted out at close. ie, you bring your money, the bank gets what they have coming, the realtor gets what they have coming (if there's one involved) and the seller gets the rest.

Understand the fees involved and calculate the total cost for an entire year of management so you can compare the different managers.