Hm, itchy scalp at week 3 actually sounds pretty common with rice water, so you're probably not fermenting it wrong. Fermenting longer than a day or so can make it more irritating though, so try a shorter soak and see if that helps.

Man that old timer probably saved your whole day, rolled joints on a firetube can be a nightmare when they keep weeping. We've all been there fighting a leak that just won't quit, so glad it worked out for you.

Whole sticker as a QR code sounds like a mistake to me. Part of why 40 people scanned it is because the funny line made them stop and look. A plain black and white square gives nobody a reason to care. You lose the joke, you lose the attention, then nobody scans anything. Keep the line, just make the code a bit bigger if you want more hits.