1) What on happens on pages 95-96? How is this ironic?

Specific pages are difficult because copies vary. I'll go with the fact that the Twins see a "beast" but it's really a dead pilot. It is human which is the dark irony that Golding is trying to illustrate through Simon's belief of the beast as being "at once heroic and sick."

This section is filled with irony;

The dead parachitist lands on the mountain;

ironic, the boys are struggling to build a society while the adults in the world are killing their own.

another irony is that he gives the boy's fear of the beast credence; like the beast, the parachutest causes fear. In both cases it's fear of the unknown.