Being able to evaluate the market analysis and even examine ARV options based on sale price/renovation costs and MLS/AVM comparables. 

Oops, I think I hit a nerve.

If you are in a tight budget don't forget the permits and architectural drawings will add considerably to the cost along with increases in material and labor, so examine all the numbers and consider markets outside of California if you want CF.

Yes it is a little nerve racking because I've never done any of those things you mentioned before.

As to whether you have a legal 3 unit or 4 unit building a simple examination of a few documents such a deed, tax records, and assessors records could probably discover this for you. 

I've been investing since 1997, I worked in title a decade before I opened my own title insurance and escrow company, I personally trained my staff including examiners, developed continuing education courses for real estate agents blah blah blah, Let's say I could toot my own horn. 

I'm wracking my brain trying to figure it out and interested to know.

Must have hit a nerve! 

Nothing really...... its always still a little nerve racking with a little voice in your head "did I pick the best one", but that's about it.

Everyone feels those nerves early on.