If you hold it in a bank account there is 0 risk but also very little return.

Or put in my personal retirement brokerage account?

Though, 3.5% down definitely helps out a lot in getting into the game quicker, it does carry PMI upfront premium and annual MIP that I'm not sure whether it will help or hurt me in the long run.Any thoughts about this?

Now you have not had to set up a account with the local water board and pay a turn on fee.

Looks like E&O in California is about 800-1000 annually.

Account Closed, we'll need more info (i.e. full numbers) to offer any real help.

Those funds can be cash from his own or a friend or partner's bank account, or they can be from a transactional funder. 

My colleague Stephen Thomas for acting as my accountability partner as we both did our first deal during the same time frame.

I tried to open my first business checking account today for my new LLC at a credit union. 

I am renting the property as an Airbnb so I created an LLC and all the income is going to the LLC bank account currently.