i have identified the function to automatically build the usergroup cache on install, and it will be included in 1.2 for convenience
wilburshere, this sounds like an improperly performed class_dm_threadpost.php file. If possible, you may want to start with a fresh version and apply the file edits again. If this doesnt work, please PM me and we will work on it together.
to display in the memberlist, go to the global options and select "Display in memberlist"
I also notice a lot of people are missing key $template_hook variables inside their templates. Without them I cant add things via plugin, and they have to be done manually. The default vbulletin style includes them, but I guess custom style makers leave them out.