What should I know about Dutch culture?

My grandparents lived in The Netherlands for a while about 45 years ago. While they were there, they babysat a young girl. Fast-forward to today. Said young girl is now the mother of a 23 year old young woman who is coming to the US to live with my grandparents for three to four months.

They have charged me with being her “American attendant” of sorts while she is here. We’ve talked extensively on facebook and become good friends her English is impeccable and she is very Americanized and interested in American culture. However, I’d like to make her as comfortable and at-home as possible while she is here, and I’d like to be a good host and show her that I am informed and aware of her home country and culture.

Knowing this, Fluther, what are some Dutch customs, phrases, traditions, etc. that I should be aware of to make her American adventure more comfortable and fun? General facts about Dutch culture and history are also welcome. Thanks in advance!