@Jonathan Williams I enjoy using spotfire as well but it cost a pretty penny.  

You can get for free ( that is no additional cost) a review of your contracts.

Really there are manual reading (lowest cost), radio read systems that the owner will do similar to municipalities (generally highest cost as you have to buy the software and radio reading hardware) and finally automated reading where the submetering company reads the meter for you and generates the water bill.

Direct mail works when done in volume and consistently, but does cost a bit more. 

It will cost a lot to build the DADU and yes appreciation will eventually catch up but you’re moving on with your life and $600,000+ house + $ for the DADU if you build that is an expensive way to start a real estate portfolio.

I do the credit check myself and expense the cost as part of doing business. 

The down side is mostly time constraint, and any unforeseen snags along the way could cost a lot more time and money.

High yield savings account or CD or treasuries at close to 5%, so over the 4 years you have at least the 25K opportunity cost as a base case...

This is the structure I own my 3 high end properties in Costa Rica.

In Contra Costa ADUs have to be all electric, so no gas.