Where can I see an overview of the rest of my teammates?

Depending on your role in the team, you can access a different type of teammates overview.

Where can the team owner find an overview of the team?

Below is the overview of all team members and viewers (including only those invited who have yet to be accepted or deactivated) that a team owner can access. It can be viewed by clicking on the Team tab at the top menu:

Where can a member or viewer find an overview of the team?

Both team members and viewers will receive invitations by email when they are added to a team by the team owner. Only after accepting it will they be allowed to join the team and see their team's folder in the folders' sidebar under the Documents tab:

The team folder provides the team's overview for a team member or viewer:

Read more about the team folder and how you can use it here.