Voltage and Current along a Wire
To try to answer your actual questions:

1 - Current is not "the actual flow of charge carriers" any more than sound is the actual movement of air molecules.  To equalize a potential difference between points A and B, it is not necessary for any of the charge carriers originally at point A to show up at point B (just as none of the air molecules at a sound source actually make it to your ear).  Maybe a better analogy is turning on the faucet at the kitchen sink.  When you do this, the pressure at the spout is less than the pressure in the water main and this forces water to come out.  But, in the time it takes to fill a glass, no water that was previously in the main will make it out of the spout.

2 - There is no such thing as an "immediate response of the charge carriers".  Nothing "real" moves from place to place faster than the speed of light.  Thus, when you consider frequencies with wavelengths comparable to the physical size of your conductor, potentials and currents will be different at different places.  Don't let anyone tell you otherwise.