He owns a building with a store front and office on the bottom level.

Mcdonald's most of their stores are franchised.

I’d like to understand what options there are out there for sending letters via an online portal where I can store tenants’ names and addresses, enter a form or custom letter, and have the service send it on my behalf for day-day communications.

Sorry, I should have clarified that the new business is a grocery store and deli.

The adjacent building is a vacant retail store (which is also for sale), behind the building is older housing, mostly in the $30-40K range, and across the street are some retail, liquor store, and a bar and grill.

They do that by doing exactly what they did to you, as much as they are allowed - and to a lot of people.Here's what I'd advise: get the electronic copy of whatever camera scoping they did.In my case, after asking, they didn't provide.Go rent a big auger from the local big box store with a Rental Center. 

This means that you can buy and store the metals yourself... you can store the coins in your own home..."

I don’t make much money I’m working in retail store and I moved because I got layoffs in Virginia.

How far is it to Walmart/major grocery stores?  

I would highly recommend Brandon's book on this topic - The Book on Investing in Real Estate with No and Low Money Down - along with Matt Faircloth's book Raising Private CapitalBoth can be found on Amazon or at this BP link: https://www.biggerpockets.com/store