For the relays, I used 8 of these. They are solid state relays, good for about 100watts AC. They're nice and high impedance, and draw about 17ma, so I can run them directly off the CPU pins of the Arduino with no extra circuitry.
I can't see it on the picture, but do they have an internal diode, or did you put one on? There must be one to prevent the coil from slapping the arduino back.