#1
HEy guys i got an amp here (peavey blazer 158) it has a reverb dial but i have no idea of what that is any info guys
#3
Basically what smash_your_mom said, I generally use it for when I'm playing on the D, G or B strings, if you stretch the notes out it can sound quite cool.

Also, some decent sounds if you start tapping with it up high (like around 8 on your amp).

If you listen to Mars Volta, you'll know from songs like 'Eriatarka' that Omar uses reverb a lot.