I remember that Snupin piece and I loved it! I always envy how you do your shading with hatching. I am completely incapable of doing that. But I do mine smooth, so I guess that's nice too. But your work always looks so effortless.
Regarding #6: Yes, at the time I wondered why Harry couldn't do a simple spell just to help Snape. It seemed as though Harry had come so far, had seemed to have learned so much and matured....yet, he just watched Snape die without lifting a finger. Seemed odd to me.