They determine the property's worth based on its net operating income divided by the purchase price.

Property in question is a total of 25acres divided in two tracks for sale.

The totality of my plan is to divide 3 equal lots, build economical but marketable homes on each, rent/sell them, then use the equity from them to collateral our forever home on the remainder of the property.

The backyard is already divided into 2 parts and has plenty of space for an ADU.

Duplexes sometimes come in a little lower per unit since you’re building two under one roof, but it really depends on the design and land costs.A good way to get a ballpark is to look up recent sales of new construction in Gilbert or nearby cities on Zillow/Redfin and divide the price by the square footage, which will give you a real-world snapshot.

Butchers hill is the dividing line between desirable to the south, to some issues to the north.

It is entirely dependent on the variables above for each and every monthThe amount of interest paid in each payment is: the interest rate of the loan multiplied by the outstanding balance at the beginning of the period, and then divided by 12.

Net Operating Income divided by the prevailing cap rate gives you an estimated value of the property.  

Should I just sub-divide the land and build a duplex on the land and move in one side, rent out the other, and then rent out my single family home?

Try taking the replacement cost of every major system and dividing it by the remaining lifetime of every item.