I don't know if they are compatible, but you might look at getting an Apple notebook keyboard. Some eBay sellers sell just the keyboard.
No. Keyboards are almost never compatible across manufacturers. Usualy you just get a ribbon flexible membrane out, which plugs into the motherboard. The keyboard controller is on the motherboard.
You have a few options.
1. Sandpaper off the legend and try to custom paint/laser it yourself (I don't think WASDkeyboards will be able to laser it, but you can always ask, I guess)
2. Pry an actual apple key off one of their keyborads, and modify the "scissor-holding" latches on the bottom to accept the ones on your HP.
3. Get stickers.
Also, please don't break your HP, they are terrible to take apart and repair, so on behalf of all the HP repair techs, make sure you don't break it. (though the 8560p is worse, IMO)