I am open to trying what you do with the higher price on one of my properties just to test it.

ADU construction is not 1:1. meaning investing 250k into your property by ADU will likekly not increase your property value by 250k.

You should vet the company to ensure they have the resources to pay the rent.You ALWAYS do background checks on the people living in your property because if you let in an axe murderer and they harm someone, you are likely to get sued.Whether or not you charge an application fee is up to you.  

Hi guys, I'm looking at buying my first multifamily in the US, I've found some nice new construction properties in the Independence Heights area of Houston Texas (around $500K).

Purchase price: $410,000 I bought this property during COVID-19 when everyone was running away from buying rental units.

Hard to say much without seeing the property.

For example the HA will inspect the property every year to make sure it is up to standards. 

I have been an investor for over a decade and helping other investors (many OOS) buy and sell investment properties here in the Dallas/Ft.

I have owned single family rental properties for several years, but am now faced with a unique problem.  

If you want to stay in your house, then your only option would be to leverage equity which will probably be in the 8-10% interest rate range.Not knowing the entire situation, I think you could consider downsizing and then using the proceeds to buy a 2-4 unit property and start making $40-75K right away with still no debt.