First, I recommend clarifying your overall financial goals.

The first step to getting started is to set your goals for buying your first property, develop your buying criteria (buy box), and then connect with an agent & lender to see what you qualify for.

They are professionally managed with audited financials and you can trade in / out of them at will with minimal transaction costs.  

You definitely need the latest financials, rent roll, and staff profile to start analyzing it.

Depends on your market, but in general I would not trade market rent for vacancy unless I was in danger of losing the property or otherwise in financial distress and no vacancy was a necessity.

I have been here for 5 years, bought property and built.

For resources, you'll want to listen to RE podcasts such as BP and any local ones, read books such as rental property investing by Brandon Turner, and set for life by Scott trench.I'd also look to attend local investing meetups and learn as much as possible and network with other investors, real estate agents, and lenders 

I am under contract for a property out in Columbus and they are one of the few property management companies I am considering going with! 

How many QBOs you need depends on your entity structure rather than how many properties you have.

For me it's always been a financial decision.