Which bike are we talking about? A crack in the head tube looks like pretty rare for me, where in the headtube? in the front or in the back?. Never seen a crank in there to tell you the truth, secondly it could not even been a crack, some giants for example were returned because of cracks and happened that were cracks in the paint job only and the frames were intact after sanding the cracked area.
I would call to the manufacturer 1st and if the frame is painted like a giant of a trek for example i would sand the paint off because paint cranks also. The other thing is that many times what u see outside is a layer of carbon to make the bike look good and is not the real carbon and is not doing a single besides working for the looking of the frame.
Hope your frame is still under warranty and if it is really a crack (i'm sure the store will tell you that is cracked, just like when u take the car to the dealer because of a brake pad and they call you telling you that the transmission is dead and needs to be replaced, just making a point) what u have to do is take your time choosing a good frame and look at the models for last year because they are still on sale.
Regarding the parts i would move them over to the new frame if they are ok, probably it is time for a non forced upgrade?
Thanks