Tami, if this is a public school you should really check the story with the teacher first. I've been on the wrong end of "religious material in the schools" more than once when I was teaching in public schools, and since I was a foreign language teacher and so many of the customs were tied up in religion it was really tough
Crafts are hard to manage, and time may be short so plan carefully!
Enjoy it! And it gets easier as they get older. I have been room parent for my big DS for 3 years running (middle school) and at that age they are just happy for as much food as you can shovel their way

I do know that in the schools in our town where my neighbors' kids go, the bar is set quite high for the room parents in terms of crafts, gifts and food. Yikes! Talk to some other room parents in the school to find out what's customary there.