I don't charge an application fee per se; I tell the tenant that if I approve their application based on their employment and rental history, I will then run a background check at $25 per adult applicant.

I've spent a good portion of my adult life living and working in Africa, although I'm a US citizen.

HUD rules mandate that the adults on the lease match the adults on the voucher, so you're in the clear mandating that if they are going to use a voucher on your rental, it needs to include all residents, just as any other applicant would need to. 

Brandon,When we rent to anyone who is the only adult, we add the following clause and have them add a name, address, and phone:In the event of abandonment, arrest or death, the following person has the authority to decide when to terminate tenancy and how to store/distribute my belongings:May be something to consider, then you can talk about their wishes before it comes up.  

Any tips on how to represent ourselves as a reputable wholesalers when we are still young adults?

Is it recommended that we run a credit and background on all adult occupants or just the one who will be signing the lease?

Odd question but I was wondering if u can refuse to rent to a person with a kid or make your properties adult only?

What emergencies will occur that an adult can't handle?

My older brother and I have been in construction our whole adult life.  

I lived the majority of my adult life in Los Angeles, CA.