Carbon paste on saddle rails? No. Reason is load path. There is really little shear force on saddle rails...load direction is almost pure bending.

Carbon paste on seat post and handlebar clamp whether you ride carbon or not? Every day.

2 bolt saddle clamp torque? On a 2 bolt clamp which is the best out there...bolt torque should be relatively light and 'equivalent'...not one bolt tighter than another. Simple physics. If you don't have equivalent bolt torque front and back, first time you hit a big bump seated you will hear a god awful screech as the clamp rotates and torque on both sides of the clamp reaches equilibrium.


HTH