That is not really duplicate content, and you won't get penalised by search engines for it, if that was your concern. If anything, it aids their indexing of your site because you can show the top content in different forms (e.g. the first page of newest questions and the first page of active questions).
Although I didn't know that you could have all those sorting options in categories as well, that could be a little confusing for users to have so much.
You can remove menu items in the admin section, so you could turn off the "Activity" page. I don't think you can turn off "Questions" because that is the full paginated list, whereas the others are just a single page of recent questions.
Also, if you are really converned about Google indexing those pages, why not block them in robots.txt? Something like the following:
And so on for all your categories.