Although , double closing is more expensive , I feel it’s a little more legitimate than assigning.

There ARE people able to create enough hype, misdirection, and lies to successfully conduct a “Capital raise” without possessing the experience, education, knowledge and analytical ability necessary to have a fair shot at success.  

The foundation of this comes from the loan- your knowledge of the loan.

Pick an area that is within a 2 hour drive or a 3 hour nonstop plane flight.Get in that market and really learn it neighborhood by neighborhood block by block.Local market knowledge is every investor’s competitive advantage.I do MF deals in Greenville SC where I live and already own 400 doors.

There is no "secret" that the big boys are doing necessarily, just incremental pieces of information, relationships, and knowledge that have been built up over time at scale. 

This community is full of helpful resources and knowledgable professionals eager to assist during your journey.Have you chosen a brokerage yet? 

There's no true data source that aggregate all the data that you look for (at least to my knowledge).

Is it better to find one that's close to where I live (Fairfax, VA), or one that has knowledge of the local jurisdictions that my properties will need to adhere to?

I am in SoCal and Detroit has been in my mind but have zero knowledge about the market.

Definitely there is a lot of opportunity for him to learn a lot from this property if he is receptive to acquiring the knowledge.