Interesting... at first I was at a loss, but maybe there's some fun stuff I can think of...
What's your first post/topic?
Hard to get fancy with this, so I dunno.... maybe just a laconic style topic/post.
What would you say?
"<-- Discuss."
What would you do?
Honestly? At first, I'd explore around the various admin interfaces, learn what I could. Also, I'd do admin stuff, moderate, maintain, etc. If I was also administrator for the whole website & server I'd be right into that since I've not managed that before. Keeping that in mind, I would definitely not be touching anything until I was on top of how it works... if at all. Since this is 24 hrs, I'd probably say that's just a look but don't touch scenario.
Then I'd make avatars slightly bigger, cause I spent ages making mine and you can't see it properly. 
What would you change?
Hmm... I think it'd be nice to have something for the associates. As I see it that's a little thing that says "these people are contributing members, valuable to have around." The scanner I guess is already like this, but maybe something like a group projects idea where they can collaborate (probably hard to get going or maintain) or simply a forum they get access to where questions and requests can be made, and since they're self demonstrated to be worthwhile members, that'll get bigger explanations, more attention, links to resources and a better answer, since they're guaranteed to be that much more worth making extra time for: they're proven members I guess.
What skin would you choose as default?
Okay, I just explored them. I'd keep it at DarkEnergy. DarkMatter is kind of cool, but that much dark red looks wierd. Plus the angled bars all over annoy me.
Which member would you warn cause he's been really getting on your nerves this last couple of days?
PongLenis. Sorry bud, but I will say I already told him off and he took it like a champ and was decent thereafter.
Which member would you ban?
All accounts like this:
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Okay, here's a link in with my "stuff for associates etc" idea:
I'd also dump a bunch of data from these accounts, for fun, research and profit and turn it into a little project for us all. Number 1, I'd pull out all the login, visiting time data, all of that, build up a nice little csv file detailing their login and viewing history, enough to gauge when and how often they looked at the board and maybe what they looked at (probably too huge). I'd separate out the IP's, but keep it recoverable if needed, same with email addresses, and possibly login names (I'd use unique ID's for reference), because guess what, I'm also dumping the password hashes for all those unused idle accounts (especially the ones that visit regularly but never post, shiiit). Password hashes are a restricted project for a subset of the membership (let's all fine tune our JTR rules, fuck 'em, the accounts are gone, never used and emails/logins are separated - no used accounts are to be dumped, 1 post = not in list).
The forum visitation data is for a more general project, maybe associates or even just everyone. We can all grab that csv file and analyse the shit out of it to see just what these guys are doing, how frequently, how much activity, is it regular, is it sporadic... what? Identify the clusters, different types, and then... well if it gets really interesting, we consider connecting it back to the ip's and see who's watching. Plus we'll learn some very legitimately interesting stuff about how people use forums, catagorisation of forums. Hell, I'd submit this kind of thing to a journal, who wants to be a published author on an academic paper? Resume's anyone? "In depth analysis of the behaviour and timing of active but idle agents on a security forum." Bam. 
What topic would you lock for good?
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You already locked my original choice, the guy asking how he can hack his schools server. I liked my advice to him though, I have my small petty fun with those guys before you condemn them to the bin. 
That was fun! 
EDIT: Another idea: do this but for HH (check the access_log for amusing shit):
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