The part of an electrical circuit that is between the electrons starting point and the point where they return to the source is called an electrical circuits "load".
Short circuits are circuits that get back to the power source unused or with the same power as put out. Using these usually blow a fuse but sometimes doesnt. Doing this with a battery can cause electrical fires.
Schematics use symbols to represent components in the circuit. Conventions are used in a schematic to represent the way electricity flows. The common convention we use is from the positive to the negative terminal. The realistic way electricity flows is from the negative to the positive terminal.
The circuit breaker will open, or "break", the circuit when the current in that circuit becomes too high, or the fuse will "blow". This gives protection.