1. You do not need any of these products... But even if you use an alum block, the aftershave could still be useful to sooth irritation, moisturize the skin, provide a cooling sensation, and have a pleasant smell. I find that the alum block can sometimes dry the skin a bit, and as others have already mentioned, may cause a bit of burning sensation.
2. The alum block may stop minor bleeding from scrapes or irritation, but the styptic pencil is better for cuts or slashes.
3. Again, you don't absolutely need any of these, but I personally have all three available in case they are needed. Another great use for the alum block is to rub on your fingers, witch will prevent them from slipping when you try to stretch your skin.