These are kind of different things. If you are asking for the ability to select a username for your affiliate account, which you can use to log in and see your statistics, get banners, etc - that is preferable to being assigned some auto-generated account name or number.

As for the linking code.... we typically just build pages, put in the code, and leave it for a good long while. It's ok if it complicated... the important thing is that we be able to link to inside pages.

Steve