For the providers I bill for, they already have an EMR/PM software in place, so they get the ERA's sent to that software. They get their checks sent to their practice and/or billing address, although the major payers are on EFT. I have never heard of the billing company getting the checks and EOB's directly sent to their location. If you are billing for a doctor across the country, how are you supposed to deposit their checks, if they use a local bank to their state, for instance?
While I don't own a billing company, the ones I work for provide all services related to billing a claim. From demo entry if needed, all the way to follow-up on claim denials, and everything in between.
Marketing should start when you are ready to provide all your services to a provider, in my opinion. You don't want to market a service you aren't ready to provide.