Only so much you can buy with cash. 

I used number 2. my neighbors neighbor need to sell house now.

That's where you may get better answers, but you also want to ask a better question to get the most out of it.How much do you know about laundromats? 

Our lot size is 7300 sq ft and main house is 1700+ sq ft.Location: San Jose, CA- We were thinking to potentially design the ADU such that we could have a wall (or a door) that allows us to separate the ADU into a 1 bed/1bath for self use (or rental) and another part which could be rented separately on AirBnB as needed.

Depending on how much liquid cash you have, you could also invest too on the side if you are looking to scale rather quickly. 

If Oklahoma has a law called "Predatory Real Estate Wholesaler Prohibition Act", don't you think that might just be a state to avoid for a new wholesaler who doesn't know much of what they are doing yet?

As you learn more, you realize how much you don’t know.

Consider all your risk (much is listd in other posts).  

How much will be due in repairs over the next five years? 

You just need a bridge loan.