Well all of those things I know how to do
But I will play along :P
1) Administrators and Moderators will be the only one to see the button/link.
2) The usergroup is set, no dynamic fancy things needed!
3) It will effect only the thread starter, possibly only if they are in the "registered users" usergroup.
4) It should only have to change the primary usergroup.
5) Its for an approval/denial setup when it comes to applications to a clan/guild/outfit, people post an application, at the top there will be a button for us to approve the application without having to go in and edit the users settings the button would do it for us
Other things that it will do is sending an e-mail to the user, a PM and also post in the thread that it has been approved, though that was a hurdle I would face when I slammed into it >_>
Thanks for replying!