Yes, “not-admin” users only see Contact, Blogs, Activities.  They can also not export all-data.  Aside from that everyone uses the core applications the same way e.g. create a task, assign it to someone, reassign if necessary (route), or click it off as completed.

Activities would be your primary “dashboard” i.e. the place to manage your next actions, monitor what has changed etc.

Do people see only their own tasks or as well the tasks of others? Can I set this?

Users can see their own items and shared items, but cannot see other users private items.  More info…  The system supports a simple workgroup model where contacts, blogs, companies are “owned” by either a user (making them private), or by a workgroup that specific users have access to (making it shared).  If the contact/blog that the task is attached to is owned by a workgroup then the users in that workgroup can access it (according to their access rights granted to workgroup e.g. read or modify).