Answer:
1. Cabin 11 is filled with Hermes kids and kids who are undetermined. Hermes is the god of messages and thieves. Percy meets Luke and some other kids.
2. It means that he is half human, half god.
3. Clarisse goes up to Percy, threatening him, and while she tries to dunk him in a toilet, he uses some sort of unknown water magic to knock her off her feet and embarrass her.
Explanation: