What are the goals of this society? Are they reasonable? How do they go about achieving them?

The primary goal is survival, and most importantly, rescue, and in Chapter Two, Ralph tells the boys that their goal while stranded shall be twofold: one, they should try to ensure their rescue, and two, they should try to have fun. He also says that their plan to be rescued requires that a fire be built on the top of the mountain, for the smoke will signal their presence to passing ships.