If it is a 110 volt light it can safely run on a 20 amp circuit with AWG # 12 wire.
Watts = Volts x Amps for an incandescant bulb. So Amps = 600/120.
The wattage of the water tank is needed to size the breaker and the wire to feed the tank.
A minimum of 15-amp breaker is "needed", but a 20-amp is often required by electrical code for that situation.
100
A 15 amp circuit breaker will handle this situation very well. The smallest home breaker is rated at 15 amp.
A 30 amp breaker wired with AWG #10 wire.
In standard construction this would require a 15 amp breaker and 14 gauge copper wire.
Normally AWG #10 wire on a 30 amp breaker but it really depends on the size of the pump. The pump manufacture will specify the size wire and size breaker needed.
The electric furnace operates on 240 volts so a two pole breaker is needed.
Need to know what the wattage or the amperage is of the appliance. The load amperage is what governs the wire size and the breaker to protect the circuit.
60amp
A 20 amp breaker might actually be needed for the installation. It depends on the wattage and voltage of the window air conditioner.