I, personally, have mixed views on this.  

@Hannah Potter Here are the things that many CPAs support their clients with:Understanding tax impact of short-term vs. long-term vs. flip before you buyWhich entity structure is best for goals and investment property typeTax and compliance on LLC or S-CorpHow to transfer property out of personal name into LLC (hard to buy 1st through entity)Ways to optimize taxes throughout the yearHow best to set up accounting to track income and expenses (doing this late is a mess)Feedback on property management systems, accounting systems. systems, etcEstimated payments to avoid penaltiesKnowing when to file and getting things in on timeMaybe a few things I missed, but this is the high-level ….. if you can get answers to the above questions on your own, plan, and file your own taxes then you can avoid the expense of a CPA.

Often ADU projects have comps where they compare the ADUs to little office spaces, personal yoga studios, etc.

Me personally, I would save up a little bit more to at least 30K.

I did a credit check, criminal background check, got pay stubs, required income 3x rent, and got employer confirmation and prior landlord reference (but I never got in touch with the prior landlord successfully)

There are several popular programs out there, but personally I like Baselane because it's specifically for real estate investors so all your transactions will fit into the Schedule E you're going to need at tax time.

One person's unique could be my ordinary, and vice versa. 

A Debt Service Coverage Ratio (DSCR) loan for investment properties is often considered better than a traditional mortgage for several reasons such as: it focuses on the property's income rather than your personal income.

CGL coverage will cover property damage, personal injury and  bodily injury but not many other issues that often arise, particularly during construction. 

If you are going to own property you need to keep a certain amount of reserves per property in an account and not touch it unless it's being used for that property.