New update on the BH&J Rent vs Buy Index. https://business.fau.edu/departments/finance/real-estate-initiative/bhj-buy-vs-rent-index/bhj-summary/Interesting to note that most major markets have officially crossed over, where renting your residence and reinvesting what you would've spent on a home makes more financial sense than buying.

@Danielle Zito We did this (reappraised a three-decker in Boston to apply for a HELOC to fund investment down payment on another, also Boston) and though rates are variable on the product we have, they're fixed for a period of time first - so paying it back is a priority.In terms of timing, it does take some time to get through the HELOC process, so you probably want to start sooner rather than later, but I would discuss with your mortgage lender as well.

One thing I’d add to the list is that utilities typically aren’t on which is risky + a major pain when you transfer title.  

I've also thought about reaching out to one of these major portfolio lenders and putting everything on more fixed long-term debt to increase my cash flow, but I like the idea of paying everything off in 15 years. 

Also, next economic downturn and you can expect some very serious, very major changes in the TX higher education landscape.

I especially like the flexibility of this type of loan product and the low interest rates. 

This will essentially tell you what happens to your return in the even of a fluctuation of a major parameter, often the occupancy rate and the achieved rent.

Municipalities will Not be common buyers for vacant land....not sure how you came to that conclusion.The vast majority of vacant land you can buy this way will have No value to a builder.....there is a reason people so often let these properties go to tax auction and it would be very difficult for you to determines the paths of growth and what would be desirable to a builder/developer.

BasicallyHow much profit can you make with rentals (apartments, duplexes, etc), and regarding loan products, how much capital would be required per year to reach my goals mentioned below? 

But the best way to get this as high as possible is to at least update something in all the major components of the house