Mississippi
Biggest river in Europe: YesBiggest river in the world: No (it is in fact the Nile, in north Africa)
No.
No. The Shannon is Ireland's longest river. There are also other rivers that are longer than the Liffey. The Liffey's importance is that Dublin, the capital city of Ireland, is built on it.
The Missouri River, which meets the mighty Mississippi in St. Louis, Missouri.