As a long time fan of SOINF, it saddens me to see the wiki in such a sorry state. I'm willing to help, but also to make some changes. With that in mind, I wish to ask: what are the requirements for promotion?
My knowledge of the first 4 books is almost complete, but I've sadly never had the chance to read 5th and 6th.
Well, if you're looking to help out by improving existing pages, this is an incomplete list of pages that need attention; you can choose the topics that you know the most about and work on those. I think the most important project right now is to improve the summaries for the books in the series.
In terms of promotion: You can do almost anything on this wiki with your current user level. I think the only major things you can't do are delete pages and edit the rights of other users. If you need to do either of those things, just let me know and I can do them for you. If you make regular contributions to the wiki, then I'd be more than happy to grant you additional powers if you think you need them!
I am aware that the Wiki is a little rough in patches; that's partly because it's been a while since the author has added to the series. Every few months the passion to improve the Wiki strikes me and I'll make a few hundred edits before hibernating again. But if you leave messages as you have done here, I will usually reply within 24h.