I even owned my company for several years in the beginning with no auto insurance and no liability insurance.

If you are going to do it, I would strongly recommend a written contract, get an estimate from him, pay only per the contract (not hourly, daily, etc), Require General Liability, Workers Comp (including coverage for him) and Auto Liability

We have our primary home, auto, and an umbrella policies with one insurance company. 

Outside and mechanicals were all in excellent condition but interior was very outdated.

The LLC is a separate entity from you and normally does not own the contents of the house.An umbrella policy provides an additional limit of Liability that kicks in when the limits of your homeowners, auto, boat, RV, ... are exhausted in a claim. 

I requested them that I will pay half the amount but they're threatening to put a Mechanic's Lien on Property for non-payment.

I set up an auto transfer from one account to the other, every month, so the reserves are set aside automatically. 

Tax Breaks (claiming deprecation on taxes due to mechanicals/roof/etc getting older).

So I’ve been dealing with one of those ‘tenant from hell’ types for the last couple years in my SFR in Moreno Valley, CA.He’s been violating city codes by illegally operating an auto repair business on the premises.He’s been notified to stop several times by the city, myself and my property management company.

Realtors setting them up on auto emails and a majority not fitting their needs.