"I have this vocal "ahh" section that I either want to sweep from left to right"
If you want to make it pan from left to right, use a pan envelope. Check out the buttons along the top of the multitrack screen. See the one (probably on the right side) that has three little white squares? Click it. See the one that says L/R? Click it. See the blue line that appears in the middle of all the tracks? That's the pan envelope. Move the line up, and it pans the track left. Move it down, and it pans it right. Okay, so pan the vocal section left at the beginning (move the line up) and right at the end (move the line down further along the track).
"or have the echo from left to right. How would I go about this?"
Not sure exactly what you want here, but you can copy the existing track. Leave the original track uneffected, but put loads of echo on the second track. Pan the second track so it goes left to right like I described above.