If you're asking for free advice from a stranger on the internet, I'd encourage you to find a different STR market unless you want to have a place in Kissimmee for personal use.

I personally wouldn't charge for any of that if they left the unit in good shape. 

Personally I feel he earned it that’s his money.

@Shiloh LundahlTheoretically assuming properties were identical in every sense yes because I don’t need cash flow and would rather have the extra $100k in equity.Now $600/mo could get you another $100k mortgage to get you another property that could potentially also cash flow but for me personally I am in equity play mode now income mode - just my personal choice but nothing wrong with the other scenario

This is a lender and personal question.Lenders look at your monthly Debt-to-Income Ratio.

And, if you find that person on the right day, you can make a deal that works for both.

Since the DADU is on the same property as my primary residence, can I place the DADU in an LLC, separate from my primary residence, to protect my personal assets from liability?

Recommendation letters would be fine as well, but personally, I think talking to them over the phone is more ideal as it's easier to get answers and just a better understanding of the tenant. 

My worry with leaving the local agency is the personal attention that guests receive when they call.

If you can't keep control of your personal finances, you are highly unlikely to succeed in real estate investing.