This question has been answered by BobRay. See the first response.
The user gets lgnActivateEmailTpl but instead of [[+confirmUrl]], I include a link that sends them to a page that has a custom snippet. (or preferably a modified ConfirmRegister if I can get it to work)
3 - I'm trying to create a basic front-end interface for an admin usergroup to view a list of newly registered users for the website. The admins could then approve the user and activate their account. I'm using 'Peoples 1.0.1' to get a list of inactive users. Then in the chunk I'm creating a submit button with a snippet and sending [[+internalKey]] variable to it. And from there I'm not sure how to set this up. I know I need to put something like $user -> set('active', '1'); but I don't know what code to put in before that to identify the user as the same one from the internalKey variable.
See this: http://forums.modx.com/index.php?topic=52526.0%3Bwap2
3. You could do that, but have you seen that admins can easily activate multiple users in Security -> Manager Users? Also, see the ActivationEmail extra, which sends an email to the user notifying them of the activation.