Goal:Determine the "Break-even" cost of having one additional adult (and dog) live in our home. 

In addition, there are 3 other adults living in the house, one of which, she mentioned has a job too. 

If you're an individual investor who owns or will be buying a single family home to rent in Metro Phoenix (and other booming Sunbelt states), good news: the big dogs with their legions of analysts think you're making a smart move...because they're doing it too.From a 10/19/20 article by Mark Heschmeyer of CoStar News:"Young adults have been fueling demand in the urban apartment market for several years.

I rent a townhouse to three adult college students on three individual leases co-signed by their parents.

Pre-COVID, I would have estimated it to rent in the $2,600-3,000 price range.Likely tenant would be a family with adults who are either govt employees or govt contractors.

Have you seen any courses / webinars etc that explain in simple steps how mixed use entertainment destinations are developed?

Forums are for entertainment purposes, not legal advice. 

That leaves the low property tax, no income tax, cheap utilities, no weather related expenses, tile roofed, stucco sided, median property age under 20 years, cheap insurance and solid foundations Las Vegas properties with lots of entertainment, very cheap flights and a good quality of life. 

I'm not an adult yet so I don't know much about basic finance and how the economy works.

Every adult generally has an automobile, so at a minimum this is needed to control parking and traffic.