Cary, I am no lawyer, but a simple answer is you use a contract that you buy or have created for that very reason.  

Any suggestions, tips, or a simple introduction would be most appreciated!

Who knows- it could be impossible or it might be simple and fairly inexpensive, but you can get a fast and free answer at city hall.

What is the typical % of operating expense over the effective gross income? 

The better operators will be able to charge more. 

Other non-code enforcement issues I look for when doing inspections on my own: change air filter, check to make sure toilets are not running, run water in sinks and check drain pipes for leaks, check for signs of unauthorized pets, check to make sure all windows operate, check all GFCI outlets with a tester and make sure they reset. 

As a result, I've put that on the back-burner now (still pseudo-operating) and started my own company to address the same key issue that I faced previously - capital constraints. 

In addition, did it cause issues with refinancing due to the property being lease hold rather than fee simple?

In Denver, you can only operate a short-term rental (Airbnb, VRBO, etc.) in your primary residence.

IMO the lower quotes aren’t always for inferior work and in fact are sometimes very good, small owner operator types like that if they work quickly and efficiently can get things done for cheaper, and having a general handyman that is good is invaluable.