If you were to create a quick 20-min training to your medics out in the field, what topics would you like to see covered?

So, I think the most important thing to remember about training is applicability. Your unit and mission should drive training more than anything after you leave the schoolhouse.
If you're in an armor unit, you'd better know how to get to both ends of every crewmember in an Abrahams. If you're assigned to an FLA team, battle drills. Do you and your partner both know the whereabouts of every piece of equipment in your rig? Can the driver anticipate the medic's needs whilst the latter is actively treating a patient? If you're a line guy for ground pounders, you'd better learn exactly what is expected of you in any contact situation. Practice movement to contact and how to evacuate casualties in concert with the unit's actions.
Another thing to remember, "we fight as we train." If you and your crew practice working out of your aid bags, your MES boxes, or whatever else you have on hand when casualties arrive during a deployment, when the excrement impacts the oscillator, you'll be less likely to waste time fumbling for the thing you need. OH, and don't forget that casualties are never, ever found laying supine with both hands parallel with the hips and toes pointed up. And it's almost as inconceivable that they'll be found inside an office door. If the medic isn't at least a little short of breath when the reach the casualty during training, you're not doing it right. :D

Focus on ABCs except when CAB and Rapid Trauma Assessment. From there one can get a quick diagnosis as well as which problems need addressing first. Make sure everyone understand and have them do a quick RTA with them telling you what they are checking. We learned (in AIT) how to do it in 2 minutes.

Absolute mastery of the basics. TCCC/MARCH. Deployment isnt the time to learn new tricks; thats what the training cycle is for.