Following is my opinion but I recommend you get the feel of the neighborhoods. 

Highly recommend investing out of state. 

I would not recommend.

If you have resources you recommend on using OPM -- I'd love to see them!

If you are trying to make it a place of business I would recommend looking into either an SBA loan or a commercial loan, or private lending.

If not, there are multiple CPAs that commented on this post that you can reach out to or I can provide a recommendation if you'd like.

You recommend that over buying RE in SDIRA?

What site or course do you recommend to start the Maryland Real estate sales person journey?

Normally in a spot like this, we would recommend to a client that you sell your primary residence and claim your capital gains exemption under Section 121, but you have two strikes against you: (1) you have not lived in this property long enough to qualify for that, and (2) I'm hoping you already claimed an exemption on the sale of your other primary residence a few months ago, and you can't claim Section 121 exemptions within 2 years of each other. 

Recommendations would be great.