Second, even we can find a land that can be re-zone to 8-unit apartment in class A/B area, the land is expensive. 

Welcome to BP @Jared Lillard, there is a lot you can learn about here at the open forum and some videos which you can access as pro member. I

I will always be grateful to my dad for stepping in to help, even though I felt ashamed to be relying on a parent at my age.

It’s money from a family member. I

You’d have to have the money seasoned in you bank account (in there for more than 60 days), the loan would also effect your DTI, I agree with the poster above, gift of equity from family member is much easier.

All websites, county records and just plain driving for dollars are tools that should be used in combination and not be relied upon singularly.

I have a property in LA that I purchased from a family member. I

I have a 5 unit that would be more than double that but you would be relying on others to look out for your interests.

A family member is going to be renting a room starting in 2018, what do I need to do in terms of paperwork/documentation, and how long do I need to rent it before I can show intent that it is an investment property?

I doubt it will be RE that leads the way.