I have to admit, I'm finding the instructions for Bootcamping an older mac a bit confusing. Some articles say you can use a Windows 10 install medium (what you created on your USB) directly; others say you have to create your own using a Windows ISO file and a USB formatted in a specific way. But then that presents its own problems, like the ISO file being too large for the type of format required. And then I found a help thread from someone with your specific computer who could never get the sound to work, even after jumping through several hoops.
Anyway, I'd be willing to experiment on my own computer, but not someone else's. I think it might be better to ask Bluebellflora for advice at this point. I'll keep looking for a good answer, but hopefully she can offer something better.
