A good guideline is that you need 3" of thread for every 1" of finished bracelet. So if you want an 8" bracelet, you would need 24" of thread, per color. I like to give myself some extra breathing room and do at least 30"

Yes, it would be the same technique as beaded kumihimo, just modified slightly to only add a few beads. Here is a video showing how to do beaded kumihimo beadaholique.com/products/how-to-braid-beaded-kumihimo-and-make-a-bracelet

If you want to create a stripe, it will be a spiral stripe as it winds around the bracelet. You would pick two colors and line them up opposite each other. Let's say you are doing orange and yellow. An orange thread would be to the left and right of the 32 and the left and right of the 16. Then a yellow thread would be to the left and right of the 8 and the left and right of the 24. You would also do a slightly different technique and you can see it here: beadaholique.com/products/spiraling-beaded-kumihimo-bracelet (you do not need to add the beads, it's the technique that you are using to get the stripe).

Thank you!!!

You just tie them on your wrist. If you use a bow, you can undo it. If you use a knot like you do with a lot of friendship bracelets, then you would cut it off when you are done wearing.