What's it like on Easter weekend in Venice. Crowds, stuff open?
Lots of people, including day trippers from other Italian towns.
Most stuff (like restaurants, bars, etc.) will be open, so you won't starve. For museum opening hours check individual museum websites.
My friends and I were in Venice over Easter weekend several years ago. I did not find the crowds to be terrible however that year it was the last weekend in March. The weather was rainy. Everything was open. We did our Doges Palace tour that day. I highly recommend going to the Basilica for mass. It was one of the highlights of my trip that year.