These are all important considerations, and understanding the requirements can save a lot of headaches down the road.

You should require the tenant to carry $100,000 liability.

What special purpose equipment do you have for an ADU/Office that required unique wiring for it to function? 

I wouldn’t worry about the higher dp because any investment property is going to require 20% down , like a DSCR  Let me know how that turns out!

As Jonathan mentioned it can be done, but they may require an appraisal of the property. 

Hi @Frank Pyle,**I am not affiliated with any of the companies mentioned**To secure long-term financing for your Airbnb, look for DSCR lenders that accept pro forma income instead of requiring 12 months of rental history.

I understand this is not a requirement, but I have never received a damaged unit from an inherited tenant or any legal issues.

We typically pay somewhere in the range of $3500 for a new, basic furnance, including install, if there are no other modifications to the system required.  

I know they are compensated per unit for the inspection, do you think it would be an issue if I just registered a fifth unit and made sure it met all the requirements?

Assuming you don't have a mortgage that requires a certain level of insurance, you can get a stop-loss policy covering all the properties.