mjjohn,
I'm actually not sure how to add a header image to an active listing. Maybe someone else will be able to help you with that.
The speel checker is working fine on our end. Please try clearing your cache via the following process and perhaps that will resolve this issue:
In Internet Explorer go to the Tools menu, click the Internet Options menu item, then click the "Delete Files" and "Delete Cookies" buttons.
In Firefox, go to Tools -> Clear Private Data -> Check Cache and Cookies -> Clear Private Data Now.
Remember to close all browser windows but one while clearing your cache.
I hope this helps=)
-Mike