do you see the article in your local copy of Zotero or just online on zotero.org?

If, as I suspect, just the latter - sync.

try switching the word plugin to classic view (click on the small arrow at the left of the quick format bar) - can you insert the item that way?

It's extremely unlikely that something wouldn't show up in the classic view that showed up in the main Zotero view. Are you sure you're looking in the same library and the same collection, sorted by the same column? If so, it's more likely that you have both Zotero Standalone and Zotero for Firefox installed and open but they're set to use different data directories (which they would by default) and you haven't synced both.

If you really think it's not working right, we'd want to debug that, but we'd need screenshots that showed the presence of the item in one and the absence in the other (which you could upload to Dropbox or a free file-sharing site like imgur.com and post a link to here).

it's not hard to get someone's attention here, so please generally start new threads on new topics, but the quick answer is that the group owner can assign admin status (and transfer ownership if needed) on the group settings page for the group here on zotero.org

yeah, that's more complicated, you want to start a new thread in the website category about this.