You can probably hold over 1000 songs on a 32 GB drive. That is a rough estimate. I'd probably recommend that size, but you could get larger or smaller based on your needs. Make sure you use the mp3 format.
Yes you can definitely do that if you have a Windows or Mac computer with a CD/DVD drive. If you have Windows, I believe you can use Windows Media player which is free. You should be able to find how-tos on Google or Youtube.