Rachsa

1. One should wash with a Bracha before eating the Matzah. The Mishnah Brurah explains that we wash again because it is likely that our hands have touched something dirty over the course of the Seder.
2. If one know that one watched one's hands and one didn't touch an area that requires Netilat Yadayim one should wash without a bracha.
3. If one is sure that one watched one’s hands from touching something that requires Netilat Yadayim then one should rewash before eating Matzah without a Bracha. According to Ashkenazim preferably one should cause oneself to need to wash one’s hands with a Bracha.
4. The Chatam Sofer had a minhag to have others wash his hands for him to symbolize freedom.

Sources

Time	Topic
Before Pesach	Month of Nissan - Shabbat HaGadol - Bedikat Chametz - Biur Chametz - Bitul Chametz - Tanit Bechorot - Erev Pesach - Selling Chametz - Erev Pesach That Fell out on Shabbat - Candle Lighting on Yom Tov - Kashering the kitchen for Pesach - Which foods, medications, cosmetics, and toiletries are Chametz? - Kitniyot - Chametz of a non-Jew - Owning Chametz on Pesach
The Seder	Kaddesh - Urchatz - Karpas - Yachatz - Maggid - Rachsa - Motzei Matzah - Maror - Korech - Shulchan Orech - Tzafun - Barech - Hallel of the Seder - Nirtzah - Kriyat Shema Al HaMitah
Pesach	- Setting the Table (The Seder plate) - Arvit of the night of Pesach - Leaning during the Seder - Required Amount of Matzah and Wine for the Seder - The four cups of wine - Matzah
After Pesach	Issru Chag - Chametz which a Jew owned on Pesach - Pesach Sheni