so, ive never been a lead guitar player, or a very proficient shredder. but lately i have been working on it. right now im working on the solo for "Two Weeks" by All That Remains.

my question is...
what would be a better picking position to have while shredding, excluding sweeps and legato, would it be better to have my pick in the vertical position like i would for trem picking, or horizontal like i would use for just about everything else?

sorry if this is worded kinda weird. its sort of hard thing to explain without showing someone.
Your trem picking technique should be the same as your normal alt. picking technique. Anyway, the exact angle depends on your preference and hand position, but usually an angle 20-45 degrees from the string is preferred. Check out this Paul Gilbert vid http://www.youtube.com/watch?v=s-NOMn3P9AE
Angling is more of a choice for the kind of sound I want. If I want it a bit scratchier sounding then I use it, if not I don't.
Angling can help a little with fast picking (at first), since the slight angle means there is a little less resistance when hitting the strings. Over time, I've found that I can pick equally fast regardless of whether I angle the pick.
The biggest thing is how you pick (rather than whether the pick is at an angle) - small, efficient movements, and just the right amount of pressure - in most cases (like when executing a fast run), the pick should feel "firm" - not a death grip, but not bouncing around from contact with the strings either.

And +1 to what which ones pink said - normal alt picking and trem picking are the same from a picking hand perspective,