Either way we will manage the property ourselves.There are a few adults (and a child) living in the occupied side.

If the best you can do is study and learn and develop some mentors while you wait to attain the adult status you need to enter into a legally binding contract, that won't be a bad thing! 

You'll have to be sure to comply with both your HOA (if there is one) and any city/county ordinances restricting the number of unrelated adults cohabiting under the same roof. 

They are adults who signed a lease.

He's was an adult, I use that term loosely and not sure of details.

On top of that we really want to be able to learn and then teach our adult children.  

I've been a contractor for most of my adult life (62 years old now), I have my Real Estate License, as well.

This is a good example of why going forward you make sure all unrelated adults over 18 are qualified individually (I state unless a dependent on another applicant's tax return, but background check still required), and a criminal/background check should have told you he has a current record so would not have been a good candidate for a tenant to begin with.    

My adult daughter loves English Bulldogs, and I know how much she's spent on them in the past! 

If you're renting to young adults who are transient, you'll probably have a lot more turnover than if you're renting to people in their 50s & 60s, etc., etc.As others have mentioned, it's also common practice to have open lines of credit ready for emergencies.