That is the basic run down, I would suggest syncing up with a real estate knowledge accountant for your specific situation! 

Financing Strategies – I’d like to put 15%–20% down—what’s the best way to secure a loan with manageable terms?

@David Matarazzo  Did either of you move forward with them for property loans?

The problem was, they only had enough money for a 3.5% down payment and an FHA loan.

If you want less leverage simply put down the funds you would use to pay down the 6.4% rate on the new property so you are at say 60% loan to value on the new house.

We worked this out with our CPA and this was his recommendation so i recommend starting with 1 account and as you grow and scale talk to your CPA and banker to see what they are seeing other investors do and what they recommend for your situation

Do 80/90% of land 100% of construction loans exist?

The lots are owned free and clear so the loan would only be for the construction.

Would this situation qualify?

In reality, it’s pretty rare to find a DSCR loan going up to 95% LTV.