S.B.
Working at a hospital in the medical records department, from my exerience, it depends on the type of coding. There are diagnostic/procedure codes and billing codes.
Our diagnostic coders are certified and have college backgrounds in medical terminology, anatomy and I don't know what all else. Those gals are extremely sharp cookies. They receive transcriptions from the physicians and apply the appropriate codes. Then there is a gal who applies/audits the billing codes for the billing department so that they can bill insurance, medicaid, medicare, private pays, etc. The billing coders don't require the same level of education and can be trained.
The diagnostic coders often work 7 days a week and often work past 8pm. (However, again, this is at a hospital and not a regular doctor's office). They sit in a little room with the door closed because their jobs require so much concentration. For instance, if someone has colon polyps removed, the diagnosis and procedure codes depend on the size and location of the polyps and all that. It's very complicated.
I think your best bet might be to ask actual physician offices what they require of their coders. You could start with your own doctor. That would give you an idea of the background required.
Working in a hospital with a physicians complex attached, I don't know any coders that work from home. I'm a little skeptical of ads you see that say you can do it at home. I'm not saying those opportunities don't actually exist, but all of the coders I know work in the office.
I hope you get some great responses. I'm interested to see them.
Best wishes.