Congratulations on having him back. I haven't seen the KERA shows mentioned, but maybe I should. lol As far as his biting goes, I would not bite. I think he is doing it out of frustration, maybe out of not being able to communicate what he really wants/needs/means. It may also be his way of getting attention for any stress he's had. It could be both.
Role play and practice with him on how to handle the situations where he's biting. If it's when he's angry, for example, then practice how to properly show our anger (take a deep breath, take a break from the situation, or whatever method you feel is correct.)
Sometimes kids use the methods that are easier because they don't know what alternatives there are. So, just take some time to practice with him on social skills. Plus, it will give you time together. :)