1 - I think that extraterrestrial life exists becouse it would be almost impossible that humans are the only inteligent species on the universe. We will contact ET'S when we're ready.The possible benefits are the advance in technology, culture, medicine and the perspective of not being alone in the universe could unite mankind as never before.
2 - In a beacon we should send aspects of our planetary culture as a "propaganda" of ourselves.
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.