That said, we’re currently cash poor.

If its a total gut, that changes things...but if it's bought right...Rehabbing will likely be your best bet. new builds set the price premium in every zip code I've ever studied. in addition new builds don't take 9 months. we just built a house in 60 days. we wait till permits are approved and shovel ready, investors buy land cash, entitle, contracts, negotiate with financing, place financing when we are ready and break ground. but we build the same over and over and don't go outside our Floorplans  

If she wants the more expensive ones again, give her the cash and she can apply it towards the cost of the more expensive version.

•Recently, I completed the cash-out refinance and received $103,000 from the bank.

It is common to offer above asking price to sweeten the pot as many owners would simply rather collect the cash upfront.What makes it a desirable offer structure?

And a price that’s a 10-20% premium over what I could sell for cash.  

If I were to open up a separate real estate bank account, I would then have to add funds consistently from my W-9 job - which in my opinion begins to blur these two accounts together anyways.Should I still open up a separate account for this first house hack, or wait until I buy the 2nd property, which would provide consistent cash flow that will go directly into that account?

I currently own 18 single-family homes in the same area (1.9m value, Cash flow avg 320 per unit).

Their father agreed to pay cash for it and my friend and I are now paying him back over the course of 6 years.

With conventional mortgage rates hovering around 7% for 30 years… cash flow basically happens at 6.5% cap rate and above.