almost every youtube video ive seen. but I have learned my lesson.

We have one as a rental and have long term tenants there who are great and we have good communication in both directions.

For the water metering- are you doing a sub meter like PUBS or are you putting in direct meters for every home?

Would need to know a bit more before giving a specific direction but it is usually best to hang on to your property and not sell whether you expand on it or rent it out and purchase a bigger property.  

I am an investor in debt DIRECTLY secured by REAL ESTATE.  

Start reaching out to landlords, you can get all their contact info using reonomy which only cost about $100 per month to get direct owner contact points.

Not a book, but Bill Faeth has a lot of free, good content on his site and YouTube videos.

Also not sure if you have a retirement fund but you may be able to setup a self directed fund and use a portion of that money for a real estate related investment. definitely not saying your plan is bad or that these are better just giving my thoughts. 

When I first started, they said I would get results if I just followed their instructions and got indoctrinated in the principles of mindset.They told me, that people actually don't learn from books, courses, sermons or watching videos, but by having a "relationship" with a coach or mentor.   

@Sarita Scherpereel runs meetups in Chicago so she may be able to point in the right direction.