RG100 ES questions

What is the difference between the low output and high output. whats the difference between switching the toggle switch up or down.

and how how can I get a heaver tone when chugging. Also what would I need for a cowboys from hell tone?

Some advice would be great

-/+ 6 db. of gain. The low gain input is generally used with active pups eg: EMG 81/85 etc. The toggle switch is used to reduce ground loop hum; so set it up or down depending on which position is the quietest. Boosting the amp increases it's tightness. The amp has a built in treble/gain boost, which is activated by pulling out the treble knob. IMO using an eq pedal in the front end of your amp with a noise gate will get you close enough to Dime's tone. But if you're looking to cop his tone from CBFH exactly:
Bill Lawrence L500 or XL500 bridge pu installed backwards-->Crybaby Wah-->MXR 6 band eq (frown curve/boosted mid setting)-->Furman PQ 4 eq (smile curve/scooped setting)-->high input-->effects loop send-->MXR 126 Flanger/Doubler-->noise gate-->effects loop return-->Randall Cabs

Thanks!

I've gotten to where i like the low input on amps better. I really have no idea why.

Some like the thighter sound of a less overdriven front end.