My favorite part of the Rental Property Calculator is being able to go back and edit the inputs. 

@Eric Swanson My favorite book in the Rich Dad series is Cash Flow Quadrant.

do you use average rent of the occupied units, average rent of all units including vacants, manually enter rent roll monthlyAs I see it, Barry Sanders, one of my favorite players of all time, there are two separate questions in there, 1: How do you account for Value Add Rent Premiums and downtime? 

When you start doing business with the intent of gaining a profit (as opposed to a hobby) you have created a business.

The Gaithersburg and Anne Arundel Meetups are 2 of my favorites.

This is all negotiable.The least favorite topic is O&P, overhead and profit.

I have my favorite sources.

Wiring is not a hobby. 

In case these were not covered I'll share my favorite options/ principles to do when you are young or starting out:- Understand that almost every successful person or person in general is working to optimize their business/life and they would benefit greatly from having more time (free time).. leverage the fact that you have the one thing everyone else needs, find the people who understand the absurd value of time and give them yours. 

From my understanding, LLCs tend to be the favorite.