They may charge you (at your age, I would not suggest paying for a mentor), or they may expect you to work for them for little or no money...if they expect you to work for them, they usually will want you to bring some proven experience and skills to the table that will benefit them--but at 19, most people don't have much experience to offer (that's not your fault, it's just an inherent part of being a young adult)....but don't worry, because even if you could find a mentor right now, a mentor might not even be the best use of your time at this stage...In some cases, a mentor might actually get in the way of your success (especially if your mentor isn't well-matched to your style, interests, goals, etc).

I require a lease to be signed, require a background check of all adults, require background check fee and am transparent about it all. 

Discuss this with me like an adult.

While your kids are too young to be employees, you could still set up investment or custodial accounts (like a UTMA or UGMA) and fund them with some of your after-tax rental income, which can grow tax-free until they’re adults.

They made an adult decision and should be held accountable.

Next thing you know you're an adult who is conditioned to the 40 hour work week.

Is it loud talking or fighting of adults?

I just read minutes on one condo O am looking at and saw a different unit had lost all amenities' access due to lewd and public adult acts. 

If he is thoughtful and responsible probably not a problem but if you are trying to help a struggling adult launch beware.

Adults don't want to share bathrooms, particularly at luxury experiences.