I admit it is a children's story for the most part, but Rowling takes it seriously and so do lots of the readers, many of which are older. Just because it appeals to kids doesn't mean inconsistencies in spell use and effects and all I elaborated on earlier are ok...

As to the Half-Blood Pure-Blood thing with the barrier on the Horcrux in the cave. If I remember correctly Regulus Black (who I still belive is R.A.B.) was a Pure-Blood from the very pure-blood Black family. So the issue of how R.A.B. got through Voldemorts defenses still remains to be seen. I havent got a clue as to how he pulled it off, since Dumbledore, who knew Voldemort better than almost anyone, needed to take his time decipherign where Voldemort's magic was in the cave. Dumbledore also is a tough one, even for an old man, and drinking that potion was impossible for him to do alone... R.a.B. had an accomplice?

As for playing defensively against Death Eaters, it does make some sense. but I just can't seem to stomach the idea that some 16 year old brats can go at it with expirienced dark wizards and not get crushed... I guess that Felix Fricius (sp?) luck potion had a lot to do with it... but that feels like a lame way to win a fight, don't it?