We will start by renting this out to my father in law.

New builds are fine, but in my opinion you're just buying something with all the priced in factors and it doesn't mean they won't have issues.

Lastly no other homes on same parcel unless ADU or mother in law but no other MH or trailers.

Investing in real estate is a lot easier when you don't have health issues, look and feel great, and have tons of energy. 

I think you would want your family to have access to money as well since there are payments due and a lot of money might be tied up in probate (this could create an issue) - life insurance and/or a shared business account could allow for payments to be made until the regular accounts are easily accessible 

My Father in law purchased his home back in the 80’s.  

But hey, it’s California…the tenant is suing me for 3x the deposit and may win.Here's my reality.

Good luck Only issue is, I'm 18 and renting w my family.

Regarding late rent, as soon as your state law and lease allow, you provide a letter stating that if the rent is not paid in full by X date, you will start eviction proceedings. 

The amount of time you will waste trying to dance around the issues will be legenday and shall I say, "insisting on being right (or insulted) when you don't know the answer can be costly".I was planning on getting a CPA, but not knowing the right questions to ask of someone who I don't exactly trust yet (as a new customer) isn't the best way to go about things.