Zipper advice

I've always been freaked out by putting a zipper on something I've knitted. Zippers don't stretch, sweaters do. I don't ever sew with jersey knits for the same reason.

So I "finished" my Urban Aran yesterday:
Before we get all giddy that a piece of very warm knit wear actually was completed in the season in which it can be worn, let's take a closer look at that collar.

Uh oh. Wonky collar-zipper shape.

So it isn't "finished" after all. I've got to re-do the neck since it is both too baggy and warped.

I'd like it to look more like this. Or this.

Here's what I think I need to do:
1. Get a different zipper. Plastic. The inside of the metal zipper scratches my chin when it is zipped all the way up. Ouch.
2. Rip out the collar. Re-knit it a bit smaller by picking up fewer stitches. And don't continue the cable pattern into the collar because it makes it flex funny, especially with the zipper.

I noticed that the other people who have made this have used 2-way zippers. I don't think I need to do this because I don't really plan to unzip from the bottom. And I'd have to mail order the zipper.

Any advice from experienced zipper installers before I embark on my knitting revisions? Is there anything else that I should change that I haven't thought of yet?