Despite maintaining my properties the biggest headache has always been the inevitable leak, HVAC failure or toilet emergency which inevitably occurs at midnight on a holiday. 

You have to make your unit attractive, well-maintained, and CMHA-compliant.

For that reason the performance of the existing stock is pretty good because they are grandfathered in.

We could pay off the house but have been holding onto a chunk of $ to see what (was hoping for some more stock volatility).

One can obtain yields far in excess of any RE investment in DeFi, just using stable coins that maintain their peg to the dollar. 

Are there any discounts or perks for maintaining multiple accounts?

I look forward to your answers and also any other general advice on keeping my cost low whilst maintaining quality with renovations would be much appreciated.Thanks!

Most of the Brandon Turner books are great.i would also read simple path to wealth to get you acquainted with more personal finance concepts and stock market info. 

The fact that some properties don’t have an HOA could be a benefit, no extra fees, but sometimes a well-managed HOA can help maintain property values and curb appeal, which matters for long-term growth.With HOA fees around $600 per year, that’s relatively low and could be worth it if the HOA is active in maintaining common areas and enforcing standards.

I'd spend probably another $1.5K to fully stock the house as a mid-term rental.