The full path to ifconfig should help you out
lxterm -e "watch -d /sbin/ifconfig eth0"
And you shouldn't need root to execute that. You would only require root if you wanted to change something like the IP/Netmask or State ( UP/DOWN )
Rather than starting multiple terminals and arranging, something I use which may or may not suit your needs is Terminator
With a little work you can setup profiles. Allowing the start of multiple terminal sessions each automatically executing commands/scripts all in one Window with multiple panes.