Fuse position in relation to load and switch
The fuse should always be the first thing a power supply hits when it gets to a circuit. The reason is pretty simple. In the event of a fault that blows the fuse, the power is isolated to where it entered the circuit, thus the whole circuit is protected. Using other configurations could allow the supply voltage into other parts of the circuit unexpectedly. There are situations where it's good to fuse both the power supply and the load, but that's another question.