Purchase price: $100,000 Cash invested: $20,000 Commercial building used to be a tire store, currently a Carquest auto parts store operating.

Recently I've tried sending a certified letter (containing all my contact info and a request for contact) with return receipt, but USPS reports they were unable to deliver it  - Notice Left (No Authorized Recipient Available)There is nothing particularly wrong, and she's completely current with rent based on auto-payments.I feel uncomfortable not being able to reach her.

Treat this the same way you would any other type of new business, whether it be a grocery store, auto repair shop or landscaping business. 

It was full of people I didn't know, including the daughter (home on a school day), the older son playing Grand Auto Theft for hours (had lost his job).

Your lease should spell out whether the lease auto renews, whether it is done at end of the lease term etc... 

Read Mike Butler's Landlording on auto pilot book.  ....or sell me your house :)  Either way....happy to answer any questions. 

If you have not been charging them for taxes and insurance all this time and you want to first start now, they will likely require a reduction in the base rent to account for the additional amounts paid to you for "CAM", so you should end up relatively even unless they are using a ton of utilities or taxes have gone up a ton, etc.You can have them direct deposit your rent, or set up an auto pay to your account.

I had all my properties with them, their auto rates were crap.

Automatically tracks mileage and can classify auto classify between business and personal travel.

Can tenants pay with auto-withdrawal?