I'm not sure how it would handle them , maybe block them, or allow a portion of them, or maybe just block the tracking cookies.

It depends on what the problem or risk factor is pertaining to those sites.

You can always try TF and see what happens , how it works for you.
If you don't care for it remove it.

Is he making much money by clicking those sites/ads?

If it is just for an activity to fill the time , maybe puzzles, safe game sites or even some kind of a hobby...

Have you looked at the cookies section on FF to see what kind of stuff is there?

[Firefox

Cookie permissions are controlled in "Tools -> Options -> Privacy". (In Firefox 3.5, you must select "Use custom settings for history" in the "Firefox will:" drop-down menu, if another option is shown.) You may choose to accept all cookies that websites wish to set or, in Firefox 3.0 and above, you may choose to accept or block third-party cookies that are often set by other companies who advertise on those sites. ]
http://kb.mozillazine.org/Cookies