Glad to help, and glad you have it figured out.
I believe you'll have better luck with the latest version of iTunes on newer hardware vs the G3! Still, it's pretty cool to read that someone is still using the PPC stuff, that's why this board is so interesting.
Sync over wifi is nice to do, iTunes has to be running on your mac of course. It's handy with a phone where you leave and come back a lot, things sync when the phone connects to the network. Once the option to sync over wifi is checked you CAN force a sync from iTunes. For example- you just downloaded some app updates to iTunes and you want to update your iOS devices without hunting them all down one at a time, you can select them from iTunes and hit 'sync.' You can also sync from the iOS device through Preferences->General-> iTunes Wi-Fi Sync.https://support.apple.com/en-us/HT203075
That's a brief overview of what it does.
It's handy, but not mandatory of course. I like to connect my devices on occasion to my iMac through the lightening cable because they get backed up onto the iMac that way.
As to podcasts- I bet you can get the podcast app (or a 3rd party one) for it if it is not already there. Can't imagine it would be different from the phone. Try searching the app store for it. I listen to podcasts on 3 different devices using iTunes on my iMac and the podcast app on iOS devices. Somehow I set it up for them to all be in sync with each other in that I can pick up from where I left off on another device. That works pretty well, sometimes podcasts I have already listened to still show up on another device as new but that's about all the issues I have had.