What new productivity tools does Lync offer?

Lync supports searching for experts with particular qualifications within SharePoint. So if an expert in a given area is needed to address questions during a SharePoint session, Lync could track one down.

Are there improved tools for managing contacts?

Yes. There is a unified contact store as well as a feature called "contact cards" that display a contacts picture and presence status through Outlook and SharePoint. A Conversation View displays a history of all communications --  voice, video, instant messaging, etc. -- that a user has had with the contact.

How does Lync improve on 911 capabilities?