We took our costumes to school through 6th grade and dressed up for our party about 30 minutes before school was out. My mom was always one of the ones who came with cupcakes & Kool-aid.
I don't think the public schools here do it now because teacher's just don't want to deal with it; that's according to my mom, who has worked at the primary school here for 25 years.
For Christmas, through 8th grade, we would either draw names or numbers every years for gift exchange. I'm pretty sure that's not done anymore either.
DD is in kindergarten and I don't see Halloween celebrations on the school's October newsletter. DD did have a Halloween party every year in the Christian daycare center she attended & they dressed up and had a Halloween parade in the church gym.