I'd review your return when you get it and see exactly what is deductible versus depreciated.

My biggest recommendation is to understand how it will appraise versus the costs of adding the ADU (the extent of any value add). 

what's the occupancy, what brings people to this property versus others, families, single people, roommates, what's the demand like for the 1 bed vs 2 beds vs 3 beds.  

Umbrellas can have some challenging requirements in order to extend those limits across multiple policies – typically requiring all policies to be through the same carrier, and be the same type of policy (ex. personal and commercial cannot mix, and admitted carrier versus excess and surplus lines carrier often cannot mix).

The article lists the following factors: The employee is paid via a W-2 versus a 1099 The employer pays all taxes The employer pays unemployment and worker’s compensation insurance The employer schedules the hours If an individual qualifies as a regular employee of the owner, the individual can manage property for that owner without holding a real estate license.

versus downtime of 3 months to rehab (cost being $34000 for purchase and $15000 rehab) and losing $1800 or more in rent, but could then charge $900 for rent?

It is hard to give you advice without having details on the property purchase versus current value.

The prices per line item change if I get only 1 or 2 of them versus all of them. 

Would probably prefer side by side, versus up down layout.  

You'll be able to utilize it differently on commercial properties versus single family homes, so your investment strategy also plays a part in this.