Fuses and circuit breakers disconnect the power when current flow is too large, but don't expect them to protect much else. The fuse will open in a fraction of a second, but a lot of damage may have already been done. Use conductors and connectors appropriate for the amount of current flowing through them and make sure all the connections are tight. Do not touch them when the circuit is or has recently been energized. Before turning on the power supply, calculate how much power the resistor will have to dissipate and make sure that it is within the rating of the resistor.
Meters are expensive, delicate, and vulnerable.
Voltmeters and ammeters usually look alike and work on the same basic principle, but they are completely different in their electrical characteristics and applications. A voltmeter has a high resistance so that a small current will flow through it when it s connected to the voltage to be measured. An ammeter, however, has a very low resistance so that there will be a small voltage across it when the current is flow through it. Voltage across, current through. DO NOT connect an ammeter across the line.