In regards to what you are experiencing with the content wrapper this looks like the regular behavior when using a rounded corners layout. The problem with the rounded corners layouts are that they work on images attached to the top and bottom of the areas. When you add to an area and increase it's size you will make a gap between the images, making it look like the background for that content area is missing.
To avoid this you should be extending the vertical size of the content area with the css fist to accommodate the text or larger content that you will include on the page.
