Thanks for the reply!
Regarding Q-1, I'm not having any luck tracking down the exact config file where changes are made. Will try looking for info on that again.
Q-2 got me digging in the right direction, I think. Short answer: no, modprobe tulip does not bring the network up by itself. Longer answer: I tried doing 'ifconfig eth0 192.168.2.2 netmask 255.255.255.0 up' after the modprobe. That allowed me to ping the router, but not anything outside. However, I noticed ifup while digging through the network script in rc5.d and gave it a shot after a reboot and it works. So now I'm down to 2 steps to get it up: a) 'modprobe tulip', b) 'ifup eth0'. (The 'ifup eth0 boot' command also works.)
If I understand the boot sequence correctly, the 'ifup eth0 boot' command is run automatically during startup. So is the problem that the tulip module isn't being loaded where it should be? Seems like a good possibility since it isn't loading at all. I'll dig into the modprobe/modules side a bit more and see where it leads.
Thanks for the shove in the right direction.
By the way, I can reproduce the eth1 line in modules.conf as I have a backup. I wasn't sure of the proper comment character for the file, so I just removed the entire line. Here is the backup file:
probeall scsi_hostadapter imm ppa
probeall usb-interface usb-uhci
alias eth1 8139too
above snd-via82xx snd-pcm-oss
alias eth0 tulip
alias sound-slot-0 via82cxxx_audio
The only difference between that and the live file is the eth1 line (note the different module).