A node just under your nock will give it strength. If your nock isn't near a node then just wrap the shaft with thread or sinew to reinforce the material and you'll be fine.
I don't use a hard and fast rule for which end to cut. If the skinny end seems too small for nocks then I'll cut from that end so I have more material to make the nock on. If the nock end is fine then I'll cut from the other end.
Arrow length is up to you. Some folks like their arrows so the back of the point is right at their fingers at full draw. Others like some more arrow hanging out there. Whatever works for you is the way to do it.
Guy