The Watermill Center will present an art exhibition, two open rehearsals, and tours of the building and grounds this weekend, beginning tomorrow at 1 p.m. with a screening at Francesca Fini’s “Ofelia No Anneka (Ophelia Did Not Drown)” and followed by an open rehearsal of “La Masca,” a mixed-media installation. Ms. Fini is a current resident at the center.