If they want the place and pass the screening process , then they sign the lease . 

First question is if I have someone who is planning to rent out a room in the house and have a signed lease agreement can this be used towards the income to purchase the house?

Im located in Phx,Az and its common here to still see empty dirt land in prime areas of city, as an example, my father who knows next to nothing about real estate purchased a 7k sqft gated dirt land  in the city 3yrs ago for $35k cash, was planning to invest in it but it was too much hassle for him so recently he sold it for $140k .What's a good way to find good deals on empty dirt land  in the city or close by, does mls offer this search option.

I now have 12-doors there and am in the process of adding a couple duplexes.I don't have much experience with moving out of state for income tax purposes but the first state that came to mind is NV.

I'd love to get details on how easy the process was, as I'm concerned about the city forcing me to get rid of the whole unit itself.

Despite these challenges, the successful sale at $39,000 highlighted the importance of strategic planning, effective marketing, and strong partnerships in achieving quick and profitable outcomes in real estate investments with Partner Driven.

(Check out  this tool to automate above process: https://stateconcile.com/) 

I want to do the most cost-effective plan for the house.

They also were extremely rude and threatening to me during the inspection process.  

go to the county permit office and see who pulled the permit or look at the plans to see who the GC is.