How can I formulate a thesis statement and three topic questions for a critical analysis of leadership roles in Lord of the Flies?

The characters in Lord of the Flies illustrate that a good leader puts the needs of the group ahead of his personal desires and respects his followers. One could develop this thesis by asking: 1. What negative qualities of good leadership does Jack display? 2. Why is Piggy not a good leader despite his intelligence? 3. What makes Ralph a good leader? 

To discuss the things that make Jack a poor leader, you can refer to his constant desire for acclaim, the way he puts his own desires above the needs of the group, and his disrespect for his followers. He gets angry when he's not in charge--which causes him to storm away after the boys fail to vote against Ralph in chapter 8. He lets the signal fire go out in order to kill the pig. At one point, in chapter 6, he tries to stifle the free speech rights of the other boys. And, of course, he uses theft and violence against the others.

Piggy is highly intelligent, which you can prove from the beginning in chapter 1 and from Ralph's statement in chapter 5 that "Piggy could think....Piggy...had brains." But Piggy lacks respect for the other boys. Although they mock him because of how different he is, he shows plenty of disdain for them, too. You can find many quotes to show how he speaks judgmentally to the others and acts superior to them.

Finally, in showing Ralph as the example of good leadership, give examples of how he puts others' needs before his own and how he respects others. In chapter 1, but he is willing to put off having fun in order to build the shelters. He also takes his role as chief seriously, coming up with rules for division of labor, fire safety, and sanitation. He keeps the signal fire in mind all the time. When someone has to be the one to go see "the beast," he volunteers to go first, despite his fear. He respects the other boys--he lets Jack take charge of the choir boys and hunting. He is willing to listen to the other boys during meetings. He also stands up for Piggy against Jack. 

Taken together, the examples of these three boys show that a good leader respects his followers and subjugates his own desires for the good of the group.