AirDNA just released an article on this that I'd highly reccomend reading.

If you're looking for a real estate book, I highly recommend "Estimating Rehab Costs" by J.

Or maybe rates stay high and he starts feeling the squeeze with his investors if/when he has to refi at 6% or sell at a price I would have paid today.Back to Bjorn's point, keep reviewing and underwriting deals.  

I highly recommend starting by tuning in to the BiggerPockets podcast.

Interestingly, these are also the qualities found in those who pursue the thrill of flying—be it through powered paragliding, ultralights, or fixed-wing gliders.I’ve discovered that my passion for the skies and my real estate investment journey share more in common than one might think.

Another clause that I would highly recommend since you are licensed is a buyer's disclosure stating that you are a licensed agent but you are acting as a principal. 

Since interest rate is now high, then IO product becomes interesting.When interest rate is above 6% ; the principal portion of the first 5-8 years is so low that it almost has no point of having principal, so IO loan product becomes (g00d)  product, BUT.....this is the but:1) if i plan to hold the house longer than 10 years hence it's better if I add principal which will reduce cashflow2) but if you plan to house longer than 15 years, and your home appreciate more than 5% yoy, just for the sake of 100 dollar cash flow, then you miss the bigger thing which is appreciation.

I don't see how building a fourplex would be any different (at a high level), assuming you have an experienced builder lined up to do the construction. 

The price was too high, initially wanted to combine the units to make a duplex.

Quads on a septic system is going to be a major expense and you should expect to pump it out every 2 years or so, so it needs a man hole cover.If it is going to be septic be SURE you have sufficient soil quality for your drain field, you will want lots of sand.