Adding a div (or two)

In creating my layout, there are two modifications that I need to make to a preset which is the closest one I could find to my desired layout. I actually have them figured out to a degree, but I would appreciate any input whether my solution is the best way to go about it, or the standard way.

1. First, I specified a full-width header with a content area of 900 pixels, centered and fixed. I want to place content in the header but keep it confined within the same width as the content. What I did was to create a div within the fullwidthHeader, fixed with 900 pixels and a margin of (0 auto 0 auto) which centers the div. I can place my content then in this div. Is this correct?

Side question: Would it be better to use a background image or insert image as a logo in this areas?
Side comment: I was trying to figure out how the layout gets centered when you select that option in the wizard. I found those margin settings in the CSS and applied them to the new div.

2. I want to place a content-width Flash movie underneath the Top nav and about the two content columns. Is it better to sort of duplicate the nav div, place another beneath it, or have the Flash within the content div? Not sure here, because the content is a two column layout.

I would like to do these things in the wizard rather than edit the CSS and/or markup as I need to export the layout to Site Assist Pro. Thanks!!

You can add with very little effort under the box tab of CSS sculptor.

In your case, I would be tempted to add a new div within the header div section, and to do this, you simply click the head div and then click the + button. If it falls in the wrong place, you can move the added div up and down or even make it a child div or stand alone div using the buttons on the right.

A good starting point for what you have described would be to use the provided template of 2 column fixed with header and footer, and then construct your div bearing on mind the size of the flash file that will eventually be sitting within it.