I'll get the first one anyway...
The taper is in there to make the bow bend properly. without it you will be weak at end of fades and hinge most likely.
On narrower bows you use more total taper because you have less taper on limb edges.
Each bow design may use different taper rate due to limb design.
For the other 2 ?s I haven't used carbon as the gain isn't worth the money to me. Not a speed hunter..
But it's reported you need to reduce stack.
Stabilcore works to give some torsional stability, I proved this to myself with the recurve I just built with the monster hooks on it. First one off the form a couple years back without it blew up first pull. This one is doing great with it under glass back and belly , except I don't like it...
Edit, I don't like the bow, the S-core is fine...