What’s the first thing I need to do & what kind of sources would I need to be successful in this?

In addition, the person's source of income is very important.

They are typically your must accurate (and valuable) source.

So negotiate with the seller and ask questions to find the true source of his pain.

Because if you did, you are the biggest hypocrite of 2019.

Usually it can be sourced to a specific fixture or room and can be isolated with a shutoff valve so that the rest of the property can get their water turned back on.

My biggest hurdle is I live in California and ROI is not really here.

I make the biggest (e.g. most expensive) version available for a year in advance, but the 1/1 is only available 90 days in advance, so in theory the smaller version only fills in the holes that remain unbooked.Re: the ADU, you may not be able to use it for an STR, but consider if you want to either have it designated as personal space for you, OR use it as an LTR?  

Could you go back to that source to get funding again?

I am getting closer and closer to pulling the trigger on my first investment property and hiring contractors is definitely at the top of my list as biggest worries.