#1
What exactly is an Amp Head for? Is it necessary to have if you're playing through a big amp like a half stack or something. I know that most of the tone and effects and whatnot can be toggled on the head but does it produce sound along with the larger amp?
Every once in a while, I'd like to be blinded by the light.
#2
The head is the actual amplifier, in a stack, the cabs are just speakers in a box. If you think about a stereo, the head is the actual system, and the cab is the speakers.

So yes, it's necessary.
"A wise man once said, never discuss philosophy or politics in a disco environment." - Frank Zappa
Quote by Jinskee
Don't question the X.
<Frenchy> I'm such a failure
#3
^ what he said. Having a head and cabinet configuration allows you more flexibility with speakers, means you can have your amps offstage and just have the speakers behind you, and I'd like to see anyone lift a 100W combo with 8x12" speakers!