Sam and Eric warn him
Samneric tell him while they are on guard at Castle Rock.
Ralph learns from Samneric that Jack plans to have his tribe hunt him the next day and that Roger has sharpened a stick at both ends.
In the book you learn some last names like Jack's but you never learn Ralph's.
Ralph learns to swim after Jack and the hunters let the signal fire go out and miss a chance to be rescued by a passing ship. The realization that they may never be rescued prompts him to take action and learn to swim to explore opportunities to escape the island.
he boy with the mulberry colored birthmark goes missing, we never learn his name however.
The chapter is called In Which I Learn to Season My Food
At the begining of the chapter, while Ralph and Piggy are bathing in the pool Ralph asked "Where's everybody?" Ralph specifically refers to Samneric and Bill, which would indicate that he believed that there were at least five boys in his group, including himself. Piggy pointed beyond the platform and replied "That's where they have gone. Jack's party." So in fact all that actually remained of Ralph's group were Ralph and Piggy. By the morning after the party, and the killing of Simon, Samneric had rejoined Ralph's group.
In chapter 9, we learn that Dimmesdale's health is beginning to fail. He looks pale and thin.
Yes they do learn
I learnt that Lan was dead
Yes. They learn where their nest is. They also learn what to ignore and how to fly.
In Chapter 7 of Lord of the Flies, we learn that Simon is a kind and intuitive character who has an understanding of the innate darkness within human nature. He retreats into the forest to seek solitude and perspective, showing his introspective and contemplative nature. Simon's interactions with the Lord of the Flies and his supernatural encounter with the 'beast' hint at his deeper understanding of the true nature of the boys' predicament on the island.