Short answers, pulled from the story.
The Neva ranks as the fourth-largest river in Europe by average discharge, after the Volga, the Danube, and the Rhine, despite being only 74 km long. This is because the Neva is the sole outlet of Lake Ladoga, which concentrates the runoff of a vast catchment basin into a single channel. The average annual discharge is 2,500 cubic metres per second.
According to recent research, the Neva began flowing between 1410 and 1250 BC, making it a geologically young river. It formed when a lake created by glacial rebound overspilled and broke into the valley of the Tosna River, linking two previously separate drainage systems and carving the Ivanovo rapids in the process.
The name Neva comes from Finnic languages. In Finnish it means poor fen, in Karelian it means watercourse, and in Estonian the cognate nõva means waterway. An alternative theory derives the name from the Indo-European word newā, meaning new.
On the 15th of July 1240, a Russian army led by the 20-year-old Prince Alexander Yaroslavich defeated a Swedish force at the confluence of the Izhora and Neva Rivers, halting a planned Swedish invasion. For his personal courage in the battle, the prince was given the honorary name Nevsky, after the river.
Three floods are classified as catastrophic: on the 7th of November 1824, water rose to 421 cm above the gauge at the Mining Institute; on the 23rd of September 1924 it reached 369 cm; and on the 10th of September 1777 it rose to 321 cm. A larger flood of 760 cm was recorded in 1691, before the city was founded.
On the 21st of August 1963, a Soviet Tu-124 airliner carrying 45 passengers and seven crew made an emergency landing on the Neva River after both engines stalled while circling St. Petersburg at 1,650 feet. The aircraft narrowly missed the city's bridges and a steam tugboat built in 1898, which then towed the plane to shore. All on board survived, and the pilot was later reinstated and awarded the Order of the Red Star.