What would be the best OS for this? 7.6? 7.5? 7.5.3?Say I would have like 8MB RAM, what about that?
I would say 7.6.1, perhaps 7.1 with gamba's suggested upgrades if you've only got 8MB.
Expect to pay obscene amounts for the rare PCMCIA adapter or a 5x0 with one in it.
Does this have an ethernet port? I mean, "Apple's" ethernet port, and if so, where do I can an adapter?
Yes, yes (it's called AAUI), and ebay or the Trading Post forum.
What about Serial->ethernet. Does that work? Where would I get it?
Yes it does - Farallon Ethertalk is one brand, and AFAIK the only one known to use the full potential speed of the Apple RS422 serial ports (around 230k/s). There were others, sold as Ethernet adapters for Localtalk printers, but they'll work with a serial Mac as well. I wouldn't bother with one if you can source an AUUI to twisted pair dongle. Beware you don't get stuck with an AAUI to coax (10base2) version.
