1. Jacob says he doesn’t want to be pack leader and that Sam was better at it; however, there were several instances of Jacob proving he’d be a great leader. What were these examples?
I don't remember. Sorry.
2. Do you think Sam was worried about Jacob being the Alpha because Jacob would prevent them from attacking the Cullens, or because Sam wasn’t ready to give up his role as pack leader?
I think it was because he didn't want to be stopped from attacking the Cullens. Sam never really has liked them, remember.
3. On both sides – the Cullens and the La Push pack – we see parallel characters. Who do you think parallels with whom and how?
4. Why is Seth the only wolf to follow Jacob? Why didn't his best friends join him?
Seth fought with Edward at the end of Eclipse and saw that Edward and his family are good people. Quil didn't go because of Claire, like Jake says. As for Embry, I have no idea, maybe he wanted to stay with his mother, or he was too chicken to do what Jake did. It was hard for Jake to do and he was born to do what he did.
5. What do you think went through the pack’s minds when Jacob left and then Seth disappeared from their minds as well?
They must have thought they'd been killed by the Cullens as soon as they left the clearing.