I would go at it from the opposite direction, look at real jobs that are being advertised for medical coding in your area and see how they work? Looks like a lot of them in my area are for temp agencies so I'd go talk to those agencies and see what the demand is and how the reality is:

http://medical-billing.jobs.net/jobs/maryland.aspx

I'd also talk to my own doctors' staff(s) and see how billing is done in their office (maybe a receptionist who'd been with the doctor for awhile took a course and worked her way up?) and what agency, if any, they use, that sort of thing.