I'm not a psychiatrist, but some of that sounds like he could be bipolar and the symptoms you are seeing are the result of a manic or hypomanic state. The epilepsy medications he's on are sometimes used for bipolar symptoms, however in my experience, Depakote (another anticonvulsive) has the best record for controlling mania. It is often used in conjunction with either an antipsychotic or another anticonvulsant medication for people with bipolar. The diazepam is also used for anxiety in bipolar. But it's possible he wouldn't need it if you added something like Depakote and it helped his other symptoms.
I would seek out a reputable pediatric psychiatrist -- perhaps your child's neurologist can recommend one he knows -- to help you sort out the non-epilepsy related issues that you are seeing and manage his medications. If it's someone your neuro knows, then it will likely be easier to have the two doctors coordinate your son's care, but it's certainly not necessary.
Also, you should take a look at http://www.thebalancedmind.org/ for good information on pediatric bipolar disorder and the various treatments that are known to help.
Keep asking questions until you are satisfied with the outcome or the answer you get! It can be a long road requiring a lot of patience and persistence, but there is help out there and you are already taking the right steps to improve your son's situation.
