increasing the reinforcement time would simply punish people using it wisely and send those units/strat into oblivion. Just disable the reinforcement while in combat would be sufficient to prevent the turtule strategy.
And fixing the emplacement/weapon taking no damage when crewed, if there isn't weapon anymore, can't reinforce!
I am not sure what you consider "wise use" if medical track and I am pretty sure the majority of player use it in similar way as a forward reinforcement healing point or even what mean by "punishing".
The fact is remain that turteling around medic tacks is currently very efficient (if not the only way to achieve victory) the it should become less efficient. Increasing reinforcement/heal time is one way to reduce that effectiveness and create room for other kinds of plays like flanking.
Not being able to reinforce during combat would simply mean that one has move his unit back for a little while and I am not sure that is enough to create room for other tactics.