I had a really old (pre-Daybreak) account. Can I get it back

I don't remember how far I got, but I'd kind of like to play that old character again.

Yes, you can get it back.

https://help.daybreakgames.com/hc/en-us/articles/217481518-How-do-I-recover-my-account-

New question: Is there an easy way to tell what other servers I may have a character on?

Unless you have the old computer with the character ini files that would say whatevername.ini.server then you will have to log into each server.

There have been a few server merges so they could be anywhere. There is a link on the help main site that shows the server merge history

Also if you ever used https://eq.magelo.com/ you can look up that character there and find out what server it is on. I have used this a couple times locating really old characters I no longer play but used Magelo to track. Even if you never used it, it might still work if you have the characters name. Just search for that character and Magelo likely has it referenced at least once from someone else input catching the server info.