There is an exiting thread for
Suggestions and requests that I check when i'm planning whats up next. I suggest you separate out your individual suggestions and post each one in there.
Bio Morphs are part of the ongoing
poll for what major feature we should add next, that would work in a rather similar way to as you suggested. Medic type classes are also part of that poll ( personally I don't think medics are a good idea, they slow the game down ).
In a game like DoD limiting the number of players using a class is no issue beacuse the choice of class costs nothing. In EX where classes are earnt limiting the number of players using a class punishes players by preventing them spending the rewards they earnt. This should be more apparent now that players are getting rewards for the damage they do.