Well, the Transcript Matching Form isn't where you put any grades, it's literally a one page piece of paper with your name and a bar code with your AADSAS number, the name of the school and the address of where to send the transcitps to.
I think you mean the "Courses Completed" section, or whatever the exact wording was. And yes, you have to list every attempt of a class that you've taken, including W's. In the grade box there is a choice for W, and then if you retook the class, the next time you list it, there is an option where you can specify that this is a retake of a class.
A few W's won't hurt you, I had like 6 on my records and it never came up at any of my interviews or anything, hehe, so don't stress! 🙂
I'm still confused where people keep getting the assumption that having a W or two is a horrible thing.