Endpoint Protection Small Business Edition

...why do we need it, what does it do?

Can we get Symantec EP to tell us if clients are running some applications that they shouldn't be, things such as P2P? (BitTorrent)?

Basically you can create firwall rules to control applications using this feature

Yes, it would show every application that runs on a PC

These may help:

Monitoring the applications and services that run on client computers

Monitoring an application to create an exception for the application

Taking this a step further. You know how exceptions are in place, can the same be done for things you want to bock, say, I want SEP to catch BitTorrent.exe

You would need to use the Application and Device Control policy for this.

The only thing you could do is create a firewall rule to block traffic to/from bittorrent.exe