-How do women impress you?
Going past the looks and whether you find the girl attractive etc. Its got to be sense of humour and if shes witty too, even better. A women with those qualities and is also confident in herself. Priceless.
-What's the worst thing a girl has ever done in an attempt to impress you, but has failed miserabley?
LOL well I had a girl ask me on Friiday if i liked babies. But that was just weird.
Back to the question, in the first year of uni, I had a girl who kept asking me if she could join in a football match we were having. I eventually said ok and tripped over the ball on her first touch and hurt her ankle. There was a lot of people watching too!!
hehe). 
A major thing with both guys and girls is you have to understand who you're talking to. If you're talking to someone who's quite intelligent, you naturally step up your conversation because you don't want to be seen as a bimbo.. and vice versa, you don't want to make the other person seem uncomfortable. talking about einsteins e=MC(squared) and how you'd like to modify that theory is not a great conversation topic with the average Tom Dick or Harry..