two questions

I am a good amature guitarist, basically. I have good technical ability, am very musical, ALOT if theory knowledge, and have good practice ethics. (Probably from studying classical piano for 11 years. I'm 16.)

1) I have been running across phrases like "sweep picking" etc...and I have no idea what this is. There are other phrases I am unfamiliar with as well..maybe someone could give me a quick rundown?

2) I have never been to a guitar teacher, and am the best guitarist i know. (And I am not that great). I need help with my grip on the pick, so I dont have to change my grip around when I pick squeal/ping a note. I dont have time when speed riffing to change grip to sqeal. Help please?

Any help is appreciated.

Sweep picking is playing (basically) a chord, except you play one note after the other, and you release each note so that you actually play a lick.
The actual technique is in your right hand, you make only one motion, and you can play up to 6 notes.
But go and check out a guitar teacher, so that you can get rid of your bad habits. (I might be wrong, someone just told me Petrucci played better than me... :( )