Win32_NetworkAdapter devices!

Hi,
I am enumerating Win32_NetworkAdapter devices on my PC using a .NET
program. I got a list of 12 devices. My PC is conected to a router.

Here is the link to the list: http://www.geocities.com/nad_af9/list.txt

Now I have several doubts about the list I got:

1) Device nº6 is WAN Miniport (PPPOE). I know that PPPOE is a
protocol, so why does it have a MAC address?

2) Device nº5, nº9 and nº12 are not physical devices, right? what are
those MAC addresses for then ?

2) How can I change MAC address for device nº6 ?