I always asked first, and never had a landlord refuse.It drove me nuts that I had no idea how many copies of the keys to my current front door were floating around in the world.

That sounds like a good idea.

My mortgage rate is very high  and I would like to pay some of it off, so that my monthly payments would go down a bit, I dont know if it is financial smart to do it or not? any advice on paying mortgage off or faster 

You've got a great start by being here and an idea of what you want to do.

I'm feeling most drawn to a buy and hold rental investing strategy and like the idea of the BRRRR strategy in tandem with VA loans, basically refinancing VA loan backed mortgages to conventional loans once there is 20% equity in the home.

Hey there @James Colgan - Love the idea of house hacking a duplex!

No, it's not a good idea, but it's possible to do correctly if you don't rush into it.

Boiled down it's the idea of owning RE without any of the theoretical "headaches" of owning it - you don't have to come up with all the funds for purchase; you don't have to manage it; you don't have to unclog toilets; ETC.

Idea is I may just sell the property the moment the project and renovation is finished.For context, the ADUs will be 2 2bed 2 bath units, 800 sq ft each, 1,600 sq ft total.

OH, no idea, only ever passed through.