Network conf mess

[Piero <ludovico.ariosto@wanadoo.fr>]

I'm having difficulties setting up my network connection.
So, I beg that someone in the list tell me where I can find very 
detailed instructions, or to give them.

I'm connected to an adsl line through a router-switch, that is in turn 
connected to an adsl modem.
My /etc/netork/interfaces file contains the two lines:

auto lo et0
iface et0 inet dhcp

dmesg shows that at boot time eth0 is assciated with the NIC that is  in 
my computer.
dhcp3 is installed.

I would like to know:

how to test if the module corresponding to the NIC is really charged

how to test if et0 is up and if it is reachable

if there is any configuration file for dhcp3

Thanks a lot, especially if you direct me to a good documentation,
Piero.