I ask because I've interviewed a number of general contractors over the years for my various real estate projects and am shocked at how the vast majority showed up to the job site to give an estimate in a vehicle that did not display their contractor license number or business name.Aside from this one issue, they'd often have great portfolios, long list of successful permits I could verify they pulled, great references, no complaints on their license, and had been licensed for over a decade.

For now all you are going to see is more of the same because the vast majority of inventory is being held by people with 4-sub 4 rates and they can't/won't want to afford elevated prices and 6+ rates.

This is actually one of the main reasons many agents and investors may not like them generally speaking (they are often not serious professionals with a proven track record of success, the vast majority are struggling to find their first deal and are time-wasters to interact with).   

However, I find myself at a crossroads, as I am unsure about which city or market to focus on due to the vast array of options available.The potential for investment seems endless, its like never ending. and I would greatly appreciate your insights into the most promising markets or cities to consider.

Now, if you are familiar with this type of investing it can be very lucrative and literally lead to vast wealth. 

.: No longer a rule, just a ghost in the past, A relic of days when profits were vast.

no way to really answer this until we know what state or counties you want to do these developments in.Each state and County can be vastly different and as such change the metrics of that whole laundry list of questions you asked. 

However as I have come to realize what I know west coast wise and what happens all across the country is vastly different.

go to Barnes and Noble or a library and look at their real estate section. 

I've listened to just about every podcast in the BP library, hell I was listening to "left field investing" before they got bought out back when they were on the "gentle art of crushing it".