My sister works with him much as part of her midtown business.

If I live a busy life and don't have the time or care to invest on my own, but want to put, lets say $200k to work, is a 15% cash flow return reasonable? 

I have just read a book about this, and a business owner spoke about his employees who would take "multiple taxi trips in one day" or "dine at the most expensive restaurants even when alone" its just something that will happen.

Hey Wes, My business partner and I are investors/agents/wholesalers in Phoenix.

"owned outright"- do the members have personal debt to support this, or is it both zero for personal and for the business?

My biggest piece of advice is the early you start treating it like a business, the faster and more smoothly you will be able to scale. 

No recourse to my credit or business credit since I'm not listed on the original mortgage.  

The business venture that went sideways?

Having trusted resources in market have been helpful in managing our properties and contractors especially when my non-real estate related consulting business is in its busy season.

While evictions are part of the business, that rate is far beyond normal.