Watch the Choose Your Weapons online guitar lesson by Angus Clark from Hard Rock Survival Guide: Rhythm
There are a lot of guitars to choose from out there and hard rock and metal have been played on just about every one of them, from Blackmore on a Strat, to Iommi's SG, Breaking Benjamin on a PRS, Schenker on a Flying V, Good Charlotte on a Music Man, Malcolm Young on a Grestch, Hetfield on an Explorer, countless players that use Kramer, Jackson, ESP, the list goes on. At the end of the day, the ultimate argument settler is going to be the Gibson Les Paul, so the bulk of this demonstration is going to be done on one. We're going to be going down to drop D and back up a lot throughout the course, so a fixed bridge is the way to go. For your amp and effects the bulk of the demonstrations are going to be done using a crunch sound. The defining characteristics of a crunch sound are there is enough gain to create sustain and possible feedback, but those elements are well under control, because silence is half of rhythm playing. You should be able to get the sound to clean up when you roll your guitar volume down. Too much gain and you will get feedback between the notes or just hiss or hum from the amp that is above the noise floor of the rest of the band. Too much gain often causes a lack of definition between the strings when you are playing chords, and actually reduces the impact of the low end of the ringing notes. If it's a one channel amp with gain, you should be at full crunch when your guitar is on 10, and then need a pedal like a Tube Screamer, OverDrive, or Booster to push you into lead territory. If it's a multi-channel amp, well the world is your oyster. If it's an amp with no gain then why did you buy it? This is a rock course!