I got a bunch of questions (6)

You can get fuses in both types glass and blade. You make the choice. Fuses come in different shapes, sizes and ratings. Only Maxi size fuse will fit in a Maxi size holder. When you are using a diode in parallel with a relay coil, you could use IN4001-in4007. Maybe you could use others too but I do not have the complete list of compatible diodes. You need this diode if your relay contacts are connecting any circuit that is sensitive such as ecu's so that the negative feedback voltage won't harm it.    A rectifier diode and a suppression/quenching diode is the same thing. They are called differently depending on what /where you use them for. Wiring up an LED with a switch is alright as long as you don't pass more than the voltage the LED can handle. Don;t put the LED in series with the switch or there will be too much current flowing through the LED and obviously burn out the LED.