I think if you keep at photoshop, you’ll be doing the most command commands repeatedly and learn them by repetition as you learn more and more. That’s how it’s been for me, so I personally don’t think specific stickers or keycaps for shortcuts or whatnot would actually work for learning. I think the dye sub set looks cool and I’d get it just because it looks cool, but not because I’d want to use it as a photoshop aid.
@CosmicKira I reckon you should wait. You’ll learn a lot (and have more fun, perhaps) by clicking around the interface and discovering tools, and you’ll pickup the shortcuts for tools you use frequently in no time.
After that, you’ll be in a better position to decide whether you want the legends as a mnemonic or because you dig them (or both :)).