Can add additional websites to the same adsense account? Does google need to approve them? How do I track different sites?
Just make sure they are all Adsense safe,, No porn, No music downloads, No Toy Story 3. You could have 20 sites, and if one was a bad apple, it might sour the rest of them.
You can add as many as sites you like as long as all of them comply with adsense policies. You can track individual sites using channels.