A guy I talk to on Skype seems to be able to kick people from a group call, even though he is not hosting. I'm 99% sure he's not getting made admin. How is he kicking people?
See the MASTER role definition on the following page:
It isn't absolutely clear from these docs whether other roles can /kick users/listeners, but it would seem the user in question must have at least a MASTER role's authority.
To find out, enter the command "/whois [Skype Name]". According to the docs, this will provide details about a chat member, including current role.