In many cases, the $/sq ft value for an ADU can be slightly discounted compared to the main home, but it still boosts overall property value.As far as the specific question about Feliz/Silverlake, maybe reach out to a local appraiser or RE agent who would be able to give you specifics.

Our home LLC in ND but it only costs about $100 and a foreign LLC is all our CPA recommended we do.  

We are also close to pulling the trigger on acquiring another nearby single family home for a second STR.

15% on a single family home and 25% on 2-4 units if you're using conventional (Fannie/Freddie) financing.

Find Brandon's videos on YouTube for the "four square" method of analyzing homes and practice.

-Will it be robust enough to track additional business expenses that are NOT tied to a single property (IE; Business insurance, Home office, ETC?)

I haven't seen prices drop too dramatically but I have seen homes in my buy box sitting on the market longer and some lowering prices. 

Home sales hit their lowest level in almost 30 years, so it's not unusual to see a property sitting on the market for many months.

Many DSCR programs require an investor to have a mortgage history- there are some DSCR mortgage programs that will work with investors who are renting- some refer to them as first time home buyers (FTHBs)- DSCR loans are only for investment properties where the owner isn't living there.

He is selling his house and the "home inspector "  says the deck wasnt built to code .