3) How many adults?

My preliminary screening is very simple: tell them we will run a full credit/criminal on every adult, they should make 3x the monthly rent income, all income must be verifiable, and we will be calling Landlord references.

The City allows up to 3 adults to live together without any issues.

A lease is a mutual agreement between consenting adults, and tenants that break that contract need to take personal responsibility for their own actions, especially ones with children. 

Zoning restrictions seem like 4 unrelated adults are the max that can live in one residence in many cities in this area.

All info on all adults living there regardless.

I inherited a tenant, and her adult daughter moved in with her, but was not included on original lease.

should I ask for an individual background check per adult applicant that will be on the lease?

We tried working with them (5 adults in a 4br SFR) for two months to no avail, they simply chose not to pay.  

While filing for eviction of a person I purchased a house from 3 years ago in Charlotte NC, of which we never had a lease, do I also have to name her adult daughter as a tenant who was living with her when I purchased the property?