QR-Code, Labels and Accessories

• Why is there an alphanumeric code next to the QR-Code?
• Is the QR Code special?
• Which QR-Code-Readers can read the QR-Code?
• What are the specs (resistance) of the standard labels?
• Do the labels leave residue? How to remove it?
• What accessories do you offer?
• Why can't I buy just an accessory item?
• How to best destroy the label?
• How to best apply the label?
• Where do I best put my sticker?