Ali, there are some mistakes in your explanation. The voltage drop across a bipolar transistor in an amplifier is Vce, not Vbe. There are two junctions there and therefore the drop is 1.2 volts, not 0.6 and certainly not some small leakage voltage. FETs are used in small minority of power amplifier designs. Vast majority use bipolar transistors.

The impedance as seen by the load is also in series as Ernie explained. This is shown in the equiv. circuit of any amplifier:



As you see, Ro (output impedance) is in series with the load.