I would also recommend that you have an actual EMT or dive medic teach you the first aid portion of your course. Having a real understanding of first aid will contribute enormously to making you an effective rescue diver. I thought I knew my stuff until I learned from an EMT instructor about the various circumstances that would require you to use the various equipment contained in a standard diving oxygen kit. "Use the demand valve one" is not really the ideal answer in all situations.
Here's a short list of things to look for in a first aid/rescue course as far as medical type stuff (from my position):
-When to use cannula, non-rebreather mask, or flow-restricted, oxygen-powered ventilation device (the "demand valve one" to most divers).
-How to perform one rescuer and two rescuer CPR.
-How to actually use a pocket mask for rescue breathing and attaching supplemental oxygen to it.
-Which flow rates are used for which pieces of oxygen delivery kit (6L, 15L, etc.)
-How to conduct a field neurological assessment.
-How to conduct a basic initial assessment (AKA the "A,B,Cs").
-Marine bites and stings, sings, symptoms, and treatments.
-How to establish incident command during a diving accident (who is in charge, and who relieves you in your care?)
-Signs and symptoms of DCS versus signs and symptoms of pulmonary barotrauma.
-The very basics of pneumothorax and tension pneumothorax.
-How to actually use and AED with two rescuers and integrate CPR into it.
-Covering how an AED is different than CPR, and why not all rhythms are shock-able.
That would be a pretty good rescue diver course from the medical aspect of it from my perspective as a WEMT. I am sure a dive instructor would have an idea what constitutes a good rescue class as far as scenarios go. I know mine involved a lot of swimming, thrashing, controlling other divers, and searches in low viz water. I am also sure that a doc would have things that he or she would want you to know, maybe if we are lucky TSandM will throw her hat into the lot.
Here is a link to DAN's field neuro PDF, which is very handy to have provided that you know how to use it effectively:
http://www.scubadiving.com/files/old/images/PDF/DAN_field_exam.pdf