Hi I did search the forum but didn't find a question exactly like this.

I want to setup a linux server that establishes a PPPoE connection to my ISP over ADSL and then provides NAT on my LAN for my various computers and mobile devices to connect to.

Specifically I want to monitor & log internet bandwidth usage by each IP/hostname on my LAN.

Ideally it would produce a CSV logging each day, with a row for each IP & hostname and it's bandwidth usage devided into the different protocols (http, https, P2P, IRC, Email, etc), then total MB in, total MB out, and total MB combined.

What bandwidth monitoring software can do this?
I've got reasonable linux skills but I'm no pro, so solutions that are easier to configure are preferable. I'm most familiar with Debian.

Check out nTop - nTop. Install and run on the internet facing interface. It will give you all the info you could want on traffic flow. I think Debian 7 comes with ntop in the repository, or you can compile ntopng which is the shiney new version, but ntop will give yhou what you need.