Milwaukee audiences, meet Anne Walaszek and Brenna Kempf. They may be undergraduate theater students at UW-Parkside, but they are key contributors to the Milwaukee Chamber Theatre's pitch-perfect production of "Bus Stop" that opened last weekend. Seeing two bright young Wisconsin actors emerge is part of the fun going on in the Cabot Theatre at the Broadway Theatre Center. Director Lisa Kornetsky's deft staging makes William Inge's character-driven comedy fly 57 years after its Broadway debut.