Corner Tsumego

It's Monday again. Time to finish things that I left last weekend. But first, let's solve a tsumego.

Black just played at the marked stone (D2) which actually a mistake. The questions are:
1. How white can punish this?
2. What is the correct move for black?

Enjoy :)

Edit: I just found out that black can also avoid being killed in the corner. The variations in this tsumego (I believe) are very useful. Have fun in exloring them :)