In my family's Seder, and in one of the two others I've been to, the reading is done by taking turns going around the table. Mostly it is read in the language of one's preference, but some (myself included) read it in Hebrew and translate the passage into English. I'm wondering what the source is for this round-robin style of reading the Haggadah (if there is a written one), and if it is widely practiced. The other Seder I've been to had the leader of the Seder reading everything all in Hebrew. Is reading by one person generally the norm? Are there other traditions?
DailyHalacha.com says that the reciting of the Hagadah is based on ‘VeHigadata LiBincha BaYom HaHu Lemor.’ The Ritvo and the Gr"a had only the head of the household read it.
Rabbi Mansour's custom however, is that all recite the Hagadah together word by word. From time to time they pause the reading, and the Ba’al Habayit or somebody that is fluent in the story, explains it in English or the language that the people around the Seder understand.
He also points out that in order to fulfill the Mitzvah of ‘VeHigadata LiBincha’, the father has to tell the story over to his children.
Well, depends on what you're referring to in Hagadah. The Hagadah has blessings (Kidush, Zmanim, Motzi, Netila, etc..) so those are usually read by the one conducting the Seder. The Hallel, Nishmat Kol Hai and Hallel Ha'Gadol are usually read by that same person as well with the others reading it silently. The rest of the Hagadah is usually read by everyone taking turns on the paragraphs.
My family is orthodox although not ultra-orthodox. I am not sure how it goes in the ultra-orthodox sect.
The Rambam (Hilcos Chometz Umatza 8:2) refers to the leader of the seder as הקורא - the reader.
ואחר כך עוקרין את השולחן, מלפני קורא ההגדה לבדו
In fact, the Rambam even has the leader of the seder read the Ma Nishtana:
וכאן הבן שואל ואומר הקורא, מה נשתנה הלילה הזה מכל הלילות וכו
This implies that the leader of the seder reads everything according to the Rambam.