I'd like to know if there is any way I can download articles on my Wikia for offline use, preferably in PDF format. Is this an appropriate place to ask this question? If not could you please point me to a stackexchange website that would be an appropriate place to ask this question.
It could be appropriate here, but it depends how it is asked. You would have to:
Be clear that it is about your administering your own website. A question like "How can I download a PDF of a Wikia article?" would be off topic, but a question like "How can I allow my visitors to download a PDF of Wikia articles for my website?" would be fine. A question about how to use Wikia from a users perspective would be better asked at the web apps site.
You would have to be careful not to ask for recommendations of third party resources such as software, plugins, or libraries. Questions that ask or these types of recommendations are off topic because they attract opinion based answers and spam. Asking "How can I do it?" is OK, but not "What plugin allows it?" If you are looking for a software recommendations there is a site for that.