You'll probably want to look into having your assets held in a living trust or some other kind of trust if wishing to avoid probate in California.As to your question about the mortgage, there's a federal law that the attorney might be referencing that generally protects transfers into a living trust from causing the need to refinance, but would need more details to discern.

This unit currently has tenants living in it.

I believe in SLC, they are still requiring the owner to live in the main house (meaning you don't have to be there, but you can't rent it) for you to use the ADU for anything else.

I live out of state from my property.

Also, the state of formation is likely where internal disputes would be brought among LLC members, so if you and a partner and/or spouse live in CA, you probably want to arbitrate in CA if the two of you had a disagreement.

@Kevin L Gleave has created a live doc that has up to date info on local meetups, I can PM you a copy (I have Kevin's permission ;) )

Say you got a neighborhood in suburban Georgia with a certain type of industry in the area, well, okay, cool, but you're gonna have a 24-year old recent Berkley graduate still living with their parents to manage the property!

Luckily, I didn’t give my real last name, and I actually live and work in Southern California so there’s little chance this will be linked to me or my case.

I know your cost of living May be higher than mine was (I live in Virginia), but the skills you develop from this will be extremely useful in many ways. 

I lived in Upper Saddle river back in 88 with my parents and remember all the beautiful homes.