Holy buckets!! You're onto Christmas and I'm still prepping for Thanksgiving. You are organized!!!
Our school did a whole school theme of Christmas Around the World last year. For sure, you should look at Mexico (Los Posadas), Sweden (St. Lucia's Day), Italy (La Befana), Holland (Sinterklasss), and Israel (Hanukkah).
A teacher idea book that would really help you is the December Idea book by Teacher's Friend Publication. Mine was written in 1986 by Karen Sevaly. But I know there are many on the market yet. It has lots of information and reproducibles for coloring & projects.
Good luck, you overachiever
