I'm looking at it on my rental software and there is also a fee for it which is the main deterrent for me currently.

Normally I would agree but if we are renting out the main house I don't want them paying for the ADU. 

I would say anytime you can add value in real estate through taking a distressed property and fixing it up and adding value it is a good choice whether its for investment or primary ownership purposes.

For tax purposes, it’s about whether you pass the 750-hour rule, the 50% rule, and meet the material participation requirements.

Yes, its mainly ordinary income from interest payments.

Quote from @Marcus Auerbach: I've researched this and I believe it's vague on purpose.

You'll see your reviews in the main body (both yours as a guest and as a host).

I don't buy from assignors for two main reasons...liability and fictitious numbers. 

Quote from @John Williams: I recently bought a home that has an attached dwelling unit where Im planning to move in and rent out the main unit.

I wrote the above for informational purposes.