1. Any small or big closed ntw can be called electrical ckt, where as electrical system usually consists of many ckts.
e.g. a bulb connected to a battery and the whole power grid.
2. In series ckt current flowing through various components is equal. The voltage is always measured between 2 pts. and whenever current flows through a resistor there is a voltage drop. So yeah when u ll observe a drop in voltage in the process from (i) to (iii).
there ll be voltage drop but the current ll remain same.