I know that the general guidance is that emergency funds aren't to be invested, but given our financial security and the fact that we already have a personal e-fund in a safe, non-volatile location, would it still be crazy/unwise to invest this 15k in an S&P500 index fund in a brokerage? 

Loan Security: The property will serve as collateral for the seller-financed loan.

In both cases to keep things clean for underwriting at the bank I used my HELOC to secure the mortgage. 

Maybe if you had a good, secure location to store things you could pre-order stuff you think you might need for your next project(s) and stockpile it.

I kept find info about it being a scam and another thing that throw me off is on one of their videos there was this guy that I seen before on another Real Estate commercial.

You've definitely come to the right place to find resources and connections.Here, you'll find several knowledgeable and experienced agents who can help guide you in securing the right property.

Its market-ready condition and strong local demand made it ideal for a fast, profitable transaction, aligning perfectly with Partner Driven’s strategy of securing high-yield properties in promising locations.

With the future being so uncertain I realized there was a need to do more than just rely on my job for financial security. 

So I did a 3-2-1 buydown and secured a 2.875% interest loan for the first year of the loan, and it will gradually go up a percent each year until it hits my rate of 5.875%!

Many view section 8 as a security blanket because of the government subsidized rent and turn to the program because the neighborhood tenant base is deemed even riskier.