Banners and html and automatic "display: none"

I am trying to make a simple page for banner exchange that contains the owner's site banner as an inline image and the "banner code" and then a list of other sites' banners that are raw html ("banner codes") typically something like:

Issue #1: preview issue

The first banner is the sites own located at http:/mysite.com/ads/myBanner.jpg. When I add the above code linking my own banner image it won't display on the page when I am logged in but will when I view the page as an anonymous user. What's more confusing is if I add the same code referring to an image/banner on some one else's server it DOES preview properly. A gif on another server won't preview either... If it were consistent seems like it would be easier to troubleshoot... Any ideas wtf is going on?

Issue #2: html code display

How do I paste the raw html snippet above as code? I managed to do it here in this forum post but when I add < code > tags on my site they get ignored and it just displays another banner image/link. I am using the default "Filtered HTML" input type with the only change being an < img > tag added to the allowed list.

Thanks for responses in advance.