What should I put in the "about me" section of an academic job talk?
The job talks I'm familiar with don't generally have an "about me" section, so you may be thinking of a different sort of talk from what I have in mind.  (I'm envisioning a research talk at a U.S. university.)  But in my experience, you shouldn't include anything in a job talk unless it illuminates your work in some way.

Hobbies are completely out, except in rare cases when they seriously influence your research.  Your career path could be relevant for conveying your background and interests.  For example, if you worked in an industrial research lab or have substantial background in another field, that could be worth highlighting.  However, there's no point in giving an oral recital of your CV.  Same thing with how you got into your field: you should mention this only if it somehow shapes how people should think about your expertise (and this will rarely be the case).  On the other hand, pointing out that your work is half collaborative and half independent sounds reasonable to me.

More generally, you want to put the specific topic you'll be discussing in the context of your broader research program.  How does it relate to other work you have done or to ongoing interests?  What's noteworthy about your overall activities?


  How much is about me as myself versus about me the professional?


It should all be about you as a professional.  You don't want to give the impression that the best argument you can make for hiring you involves your hobbies.