considering surgery for 3 yr. old son

The neurologist called last night to say they discussed my son's case at surgery conference last week and want to proceed to the next step which is placing the grid on his brain to determine exactly where the seizures originate... His seizures are in the right parietal region and involve the area which controls the movement in his left hand or arm. The grid test is most importantly to help determine to what extent if any the movement or use of his left hand and/or arm would be impacted from the surgery. He currently has complex partial seizures that are now generalizing at least once daily in his sleep. He is currently on 4 AED's and we have tried 4 others previously. A month ago he was having "inter-ictal" activity about 23 1/2 hours a day, was drooling, started walking into walls, out of control. We added Depakote and it has been very effective for him. He is doing things he hasnt done in a year and a half. He called me Mama for the first time in about 2 years :). Developmentally he is pretty much on target except for his expressive language. He is on target for receptive language, he knows what you are saying he just isnt telling you much yet :). The whole surgery thing is just so overwhelming, especially since we have seen such recent and dramatic improvement. I know though that could be shortlived or could have other side effects associated with that we have yet to experience. Besides the prospect of living life on the amount of meds he is on and still experiencing daily seizure activity is not optimal. I dont know what I am asking, I guess if anyone has any advice, any info, any suggestions on what kinds of questions to ask. They call, drop this bit of news, tell me take a day to think and call with questions, I am so overwhlemed I dont know what to ask right now. Thanks Kim