Pixar Fest is slated to start on April 13, which is the new fireworks show and the return of the Paint the Night parade. The Pixar Pier (attractions with new overlays) isn't slated to open until "summer", so it's unlikely that those will be open at that point. In terms of the crowds...I think it will be very busy in the evenings when the shows are presented, but it might not have a huge impact on day time crowds. They haven't announced whether PtN and/or the new fireworks show will run nightly or only on weekends, which will also impact crowds. If the shows are only presented on weekends, then that will concentrate the crowds on the weekends, whereas if they're presented nightly, it might distribute the crowds a little (although, I think the weekend evenings will still be very busy).