Yeah, I loved the moment Tingler talked about as well, and agreed that it was really scary!
And I also agree with your second point, TT; to me it was very unexpected, but I also liked the scene very much because of the comedy value, and the Doctor's reactions. I also enjoy the fact that some episodes have a bit at the end that is unrellated to the main story and will carry on into the next episode, making the story seem more whole.
Kroms: Silence in the Library and it's second part is essential as that was the introduction iof River Song. But you won't go wrong if you can get your hands on all of 1-4. For instance "Dalek" (series 1) is a good episode that wasn't written by Moffat. I also think that Gattis's other episodes ("The Idiot Lantern" and the Dickens one) were very good, even if peoole didn't like his Victory of the Daleks so much.
Also, Russel T Davies could write brilliantly about families and politics.