for better swing at alternate picking i do this exercise.

take any pair of fingers, from your left hand,

start with your index and middle and go on pairing eg: 1/2, 2/3, 3/4, 1/4, 2/4, 3/4....etc..

start at the first fret and work your way down till the 12th or more..

and fret the first note at the bottom e string with ur index on a down stroke, fret the 2nd fret with ur mid finger on an upstroke, go on up till the 6th string and keep going down till u reach the 12th fret. always alternate pick obviously that way ur doing a uniform exercise and can concentrate on how ur playing hand feels, if its relaxed enough, if the picking is always accurate etc....

hope that helps u out on alternate picking unfortunatley i dunno what sweep picking is yet. so i cant help u out there