During the attack, it seemed to Ralph that there were a dozen others. Why?This is all in Chapter 10 in Lord of the Flies.
You can only ask one question at a time, I had to edit your fire question out.
It feels like Ralph is going through a hallucinating transformation during this chapter. What is actually going on is as Ralph is falling asleep that night, he is having all kinds of dreams, we see the dreams recorded somewhat in the text and it feels disjointed. He dreams of being home, of even being on a bus which is not the best of civilized circumstances. But even the worst of civilization seems valuable to Ralph in his dream-like state.
As Ralph was sleeping there were a group that attacked and he associated them with what was going on in his dream. He began beating what was close to him to fight back, but the attackers had already come and gone with what they came for, Piggy's glasses. We then uncover that Ralph and Eric were fighting, not Ralph and an enemy.