The missing icons are image sources looking for an icon called icon0.gif. This can be fixed by uploading a "blank" or "spacer" (1x1 pixel transparent gif image) as icon0.gif in your vBulletin images directory.
What is happening there is this:
The person posting the topic did not specify an icon for their topic, so the ActiveTopic hack tries to look for icon0.gif, which isn't there (examine PHP code of the hack to see exactly why - oops you said you were PHP illiterate - I'm still in PHP kindergarten ).


Not sure about your deadlink threads just yet.

I have the active topics hack on the main index page of my site running vBulletin - http://www.wnsp.com/index.php3


Good luck!