If you search through some of  @Bill Gulley 's old posts you'll see a lot of discussion on Dodd-Frank, the Safe Act, etc, their objectives and the resistance to them at the time they were brought into being.

That will give you a good base understanding of most finance you need to know.For a deeper  understanding, the textbook: Real Estate Principles, a value approach by David Ling.

The best thing to do is spend the time speaking with someone who will listen to your objectives and help put together a plan that enhance your overall business plan.

@Thomas S.That would be the ultimate objective but, with the complex fully occupied, should I do that, I could be facing a very high vacancy rate until all the tenants are out.

@Mido AliIn terms of general business Principles by Ray Dalio was extremely insightful.The book on rental property investing by @Brandon Turner is one of my favorites for Real Estate.

The two lots were owned by the same person who after foreclosure, got his back end in gear and paid the liens off on the rest of his properties - so without noticing, I got 18% interest (less the service fee) on three other lots plus my principle back.This year, we sent out noticing on one lot. 

Attempting to wrap my head around the principles of "why".

IF it is a performing note then there should not be any arrears and they pay off should be the same amount as the unpaid principle balance. 

IMHO, you need to develop clearly-defined objectives inorder to formulate a strategy to achieve your objectives.

In three years you will have payed only a few thousand against the principle of your note.