I posted to you on the other thread about how to get in touch with the ADA and request that their legal advocate call you with advice. Please go over there and read mine and other posts to you.
The immediate problem is tomorrow. I think you are right to stay at the school until you are assured that there are people there who can care for him (including giving glucagon if he passes out, etc).
Without knowing more about why he was transferred and what the new school might offer it is hard to say if it is a bad thing for him to be going there in general. It sounds like he was not taken care of from a diabetes standpoint at his old school so I don't see what you're losing at this one - with the diabetes care. If his behavior issues are directly related to his poor diabetes care at school then he should not be at this school. Certainly either school he goes to needs to step up.
Go back to the previous thread someone posted for you and read what I wrote there about getting the ADA info.
mom to William, age 13, dx'd 3/04 and started pumping 10/04 - Animas 1200. Animas Ping started 01/09; T-Slim started 2/15; cgms Navigator start 4/6/09; RIP Navigator 9-1-11, Dexcom 7+start 10/11, G4 start 11/12.
and mom to Rod (17) not D