Themes aren't a problem, I can customize the look of a site myself, it's the ergonomics of it that has me scratching my head. The only "list" that really invites social interaction is Discussion.

I don't want to install Chat, as I can't police that and keep the site clean of spam and the occasional doofus.

But... I still can't find the Discussion plugin. I went through plugins for almost an hour last night and couldn't find it and a search for it only yields talk ABOUT it, not the original plugin. There must be one. We have a discussion thread here.

The "Discussions" tab here on the community site is a customization not included in the default Elgg package. But each group you create on an Elgg site can have it's own discussion section. The landing page of the Groups menu entry is the list of latest discussions then. If you would like the menu entry to be named "Discussions" instead or have a separate entry called "Discussions" beside the Groups entry that is easily possible to customize.

With the group_tools plugin you also have more options and a "latest discussions" tab in the side wide groups listing that will let people follow up on activities in all groups they have access to easily.

There is and this has discussed before. We have already given tips on how to implement this feature on that discussion. Use the search feature on top of this page, before you ask a question, so that both you and developers can save time.

Well, I guess I'll have to learn to hard code it from the previously posted example that suppresses duplicate accounts from static IPs.

I was hoping to find a solution that combines email and IP (so that dynamic IP accounts might not be prohibited entirely) and which allows duplicate accounts up to a specified limit rather than suppressing all duplicate registration attempts.

By default, Elgg wont allow users to register with duplicate emails. So there is no additional check needed for duplicate emails.