Short answers, pulled from the story.
Clan Donald takes its name from Dòmhnall Mac Raghnuill, who died around 1250. He was the grandson of Somerled, styled King of the Hebrides, and the clan's founding ancestor in the direct male line.
The Lordship of the Isles was a title held by the chiefs of Clan Donald, giving them dominion over a large arc of island and coastal territory in western Scotland. The Crown forfeited the MacDonald Earldom of Ross in 1475 and stripped the Lordship of the Isles itself in 1493.
A 2005 DNA study tested Y-chromosomes of men bearing the surnames MacDonald, MacDougall, MacAlister, and their variants. A substantial proportion shared the same Y-DNA, the R1a1 haplotype, which is regarded as often indicating Norse descent in Britain and Ireland, supporting Norse rather than purely Gaelic male-line origins.
38 unarmed MacDonalds from the Clan MacDonald of Glencoe were murdered in February 1692. Their chief, MacIain, had been late in signing an oath of allegiance to William III of England, and an initiative to suppress Jacobitism became entangled in long-standing feuding.
Four branches of Clan Donald fought for Prince Charles Edward Stuart at the Battle of Culloden in April 1746: the Clan MacDonald of Glencoe, the Clan MacDonald of Clanranald, the Clan MacDonell of Glengarry, and the Clan MacDonald of Keppoch, whose chief Alexander MacDonald of Keppoch was killed there.
Godfrey James Macdonald of Macdonald, 8th Lord Macdonald, is the current High Chief of Clan Donald. He succeeded his father in 1970 and lives at Kinloch Lodge on the Isle of Skye with his wife, the food writer Claire Macdonald.