Short answers, pulled from the story.
Jan van Eyck was born around 1380-1390, in Maaseik (then Maaseyck), a borough of the prince-bishopric of Liège, in what is now Belgium. Neither the exact date nor the exact place of his birth is documented in surviving records.
The Ghent Altarpiece is a large polyptych commissioned by the merchant Jodocus Vijdt and his wife Elisabeth Borluut. It was begun by Jan's brother Hubert van Eyck before 1426 and completed by Jan van Eyck in 1432. It was consecrated on the 6th of May 1432 at Saint Bavo Cathedral in Ghent.
ALS ICH KAN translates as "As I Can" or "As Best I Can" in Middle Dutch. It is also a pun on van Eyck's surname, and the aspirated form "ICH" reflects his native Limburgish dialect. He inscribed variations of it on at least ten signed works, sometimes written in Greek characters.
Philip the Good, Duke of Burgundy, sent van Eyck to Lisbon as part of a delegation to arrange a marriage agreement with Isabella of Portugal. Van Eyck's specific role was to paint Isabella so the Duke could assess her appearance before committing to the match. The couple married on Christmas Day of 1429.
Jan van Eyck died on the 9th of July 1441, in Bruges, and was buried in the graveyard of the Church of St Donatian. Philip the Good made a one-off payment to his widow Margaret equal to the artist's annual salary. In early 1442, Jan's brother Lambert had the body exhumed and reinterred inside St. Donatian's Cathedral.
About twenty surviving paintings are confidently attributed to van Eyck, all dated between 1432 and 1439. By the late 1990s, Holland Cotter estimated that only around two dozen works could be attributed to him with varying degrees of confidence. Of roughly forty works considered originals in the mid-1980s, around ten were later contested as workshop pieces.