Unnecessary, and yes, it will certainly count towards the page count. Sure, it makes it more organized, but it’ll make your examiner(s) think you just did that because you weren’t able to fill up all the 12 pages. Even your bibliography is part of the page count. The only section not included is your appendix, that’s it.
The first page of your IA should (first) have your title, name and session located in the header of the document, then follow by instantly introducing your research question (then personal engagement, background info, etc.) A ToC is more something you could do for an Extended Essay.