@FloatZel98: You need to double the resistance. In a way, you're right in saying that the voltage drop due to the return wire occurs 'on the way back'. However, note that the resistance for the return wires DOES change the voltage drop across EVERY COMPONENT IN THE CIRCUIT. This is because it affects total resistance and hence reduces the current flowing through what is effectively a series circuit. So in response to "The voltage drop over both resistors doesn't matter until you get up to it, which is the case here", yes that is right, but the voltage drop over everything is different because the extra resistance at the 'end' of the current's path.
It flows across the first wire until it reaches the transformer and then will never need to come back through the transformer again.
Current WILL have to flow through the transformer in the reverse direction... it will induce the current in the reverse direction that is. Current does flow in both directions over the transformers (otherwise you violate conservation of charge)
A transformer can take input voltages from either side. There is nothing in its mechanization which precludes this, that is, for the fundamental transformer concept.
3rd excited state <=> n=4 level, so 4 wavelengths around the atomic orbital. No difference, just n=1 is ground state.