1. the resistor value should be fine, but I'm not sure about wattage. I think the more leds u have connected, the higher the wattage needed. But I am not sure.
2. Yes, but I heard using a capacitor in the circuit would help stop distortion. There should be a diagram somewhere within the first 2 pages of this section.
3. a 2nd lm386 is needed for the 2nd speaker. Otherwise, both speakers will have to be mono.