what happens to the original name? Is it freed up to be reused immediately, or does it need to wait to be cleared by the system as if it was still taken?

The previous name should be usable immediately after the change. Before the name exchange function got released, many of us swapped pet names by changing their names, and I had never experienced any delays.

Awesome, thank you!

I've been here almost four years, and sometimes it seems there's still so much I don't know. ^^;

No problem! And don't feel bad. I feel like a noob every other day xD.