I'll show you the steps I took to strip it all down and refinish it. While I can't technically call this a restoration (because it wasn't returned to its original state), it looks good and is functional--which is what I was after. My kids now have a shiny new-looking wagon that will hopefully hold up to many more years of use.
It took a little time and attention but this wasn't a terribly difficult project. If you have an old red wagon that needs a little love, perhaps you can get some useful ideas from this. Thanks for taking a look.
Step 1: Disassemble wagon
The wheels were in fine shape so I left them in place on the bolsters. I highly recommend leaving the wheels on if at all possible. This saved me both time and money and I was still able to strip down and refinish the bolsters adequately with the wheels in place.
You can purchase new wheels and hub caps as well as most other parts for current wagon models at Radio Flyer's website. If you need to remove the wheels, this page on Radio Flyer's website has instructions on how to remove the hub caps. Note that they get destroyed in the process. If you're restoring an older discontinued model, finding parts may be a little more tricky but there's always eBay.