The biggest thing I'm seeing actually isn't his residency status, but I think you'll have the biggest issue with the value of the properties you are looking at.

Is there any requirement that I notify the lender that the property will no longer be my primary residence?

Below is a graph of the median list price since 2019.Contrast that to a market like Detroit where the median list price has doubled since 2019.I'm a licensed agent in Michigan, but I reside in California.

Yes I am in the Northside and unfortunately don't reside in a ADU zoning area.

I will be taking out a mortgage, but I won’t be putting 20% down and declaring it an income property, however, it will still be my primary residence.

One property is the residence of the owner. 

Investment Info:Single-family residence wholesale investment.

When we take over a property, and the rents are $400 less than what market is, as in your case, there' usually no way that resident can pay.

Investment Info:Single-family residence wholesale investment.

Life long Yorba Linda resident, because of the school system and safety Yorba Linda homes tend to rent out quickly.