#1
How do people work out how to get a specific sound....I mean there's so many variables...

Can people explain to me what each of the settings do:

Gain-I know this adds Distortion, but how much should I add for a Kings of Leon sound compared to an Avenged Sevenfold sound?

Treble?
Middle?
Bass?

How do each of these change a sound?
Tone knob on my guitar?
I sorta know the pickups but if anyone could explain better I'd appreciate it

And what is the difference between the Volume and Master knobs on my amp?
#2
THe bass, mid and treble raise/lower the overall presence of those specific frequencies.
the more bands on your eq the more tonal control.

I turn it all the way up for a more creamy sound and lower it for a harsher,less metal sound.
work with your amp and don't get stuck using one tone forever.
#4
I see that you're using the same AMP as I am. I'm also having dificulties with the setting, cause it seems you only can configure one of the presets. But I can explain the difference between volume and master:
If yours is as min, you should have two channels to choose from, where you can save your own presets. Now, the volume modifies the volume of the channel, whereas the master controls them both. So you can have 2 channels with 2 different volumes
#5
If you're trying to obtain the sound of a band recorded on a CD - good luck. Sound engineers use a lot of tricks to obtain unique sounds and you'll never be able to copy that sound at home. Recording studios have several different amps to choose from during the recording process. The sound engineer can mix the sound from several different amps to create a one-of-a-kind tone. Combine that little trick with the fact that they also have different types of mics to record the sound and you end up with a sound that can't be replicated or copied.
#6
try to google " guitar rigs" and take the first link... It's guitargeek.com, many good rigs there.. then just browse