Also important if you care about your professional revenue. I.E if you are in a democratic group where your income is tied to your billing, or any group with RVU based payment/bonusing, or even as an employee if you want your department to get all the $$$ it deserves.
ACEP has some decent overviews of this stuff, I suggest you read ALL the links on this page--
http://www.acep.org/reimbursement/
and
http://www.acep.org/pearls/
The first part is to understand what goes in a lvl 3 vs 4 vs 5 chart. Then to understand the hows / whys of Critical care billing (underused by many people). Then understand proper charting of procedures. Then understand obs (gets a bit more complicated). Once you understand all of that you are doing pretty well.
The entire obs/inpatient thing is much more of a game; helpful to have case management in department to help you with that. It does not directly tie into your reimbursement as an EP, but certainly matters to the patient and the hospital.