I think if we implement Medic's, they will most likely act in the normal fashion. This being because messing around with such a thing may upset the balance of the game... some of these suggestions would most probably require more coding and animations. Initially anyway, we may work out something once the first release is out.
On the topic of medics however, I do think, unlike the US and British who can get medics from the start, the Soviets shouldn't get medics until tier 3 to increase that vulnerability factor.
Cossacks would a cool unit to have in the game, but again, maybe not riding horses (bears, hell yes! :P )... or donkeys. Also brings up the Idea of the defected Cossacks who fought for the Wehrmacht, who's main duties were anti-partisan. We could possibly replace the Knights Cross holders with Defected Cossacks and give them a special bonus against Partisans (also being able to spot them when cloaked). Again though, this raises the question if Partisans should maybe play a larger part in the game than we first intended? I really don't know.