How does the resistance of an ohmic conductor depend on the applied voltage?

Electrons are responsible for conduction in a conductor. The speed of electron is not very high. Then, how the bulb is on immediately even through the switch and bulb are far away from each other in a household circuit?

A wire of resistance 20 Ω is bent to form a closed square. What is the resistance across a diagonal of the square?

An electric fan/motor becomes warm when continuously used for a long time. Why?

State difference between the wire used in the element of an electric heater and in a fuse wire.