In another pre-COIE storyline, Bruce Wayne learns that he has an older brother who was brain damaged as an infant and institutionalized ever since. Two-part question: What was the older brother's name, and what had happened to him when last seen?

Well, if Kal from Kansas was brain-damaged, that would explain Superman Returns. But no, that's not what I'm looking for.

Thomas Wayne Jr. Didn't he become Owlman?

Thomas Wayne Jr is correct; but he only became Owlman in the post-COIE anti-matter universe.

Is he the character that teamed up with some evil Superman twin to become the Demonic Duo?

This was all Earth B continuity, right?

Unofficially it was Earth-B, yes. There really wasn't anything in it that meant it couldn't take place on Earth-One, except for the premise being so outrageously unbelievable (but the same can be said of World's Finest #207, written by Denny O'Neill!)

I think I remember now--didn't Thomas eventually get whacked when he jumped in front of a bullet to save Batman?

Yep, that's it. Just prior to that Deadman tried to take permanent possession of his body. All yours, Kal.

Well, he DOES wear his undies on the outside.

Heck, I saw a teenager the other day at the supermarket, and he was wearing his undies outside of his jeans. That's not style, that's just stupid.

During one particular Elseworlds tale, Batman helped fight Confederate forces during the Civil War. What real life person helped him out on that mission?

To clarify: He helped fight AGAINST the Confederate forces.

Unless you were shocked that he was fighting for the North.

Strom Thurmond? No, wait, he was on the other side.