Server :: Multiple Network Cards In LAMP Stack - How To Monitor

I'm wondering a couple of things about my LAMP stacks:

1) How do I get a list of all the network cards installed in a linux box? I've run this command and it shows 2 network cards which is probably all of them:
Code:
mii-tool -v

2) How can I check the percent utilization of a given network card? I.e., at any given time, what linux command will tell me the how much of a network card's bandwidth is being consumed? I've checked both ethtool and mii-tool and I don't really see any helpful stats.

3) How can I make sure that a linux box will optimally use both network cards? I'm a bit fuzzy on how IP addresses and network cards and hostnames work together.