Short answers, pulled from the story.
Publius Quinctilius Varus commanded the Roman army during the battle. He was appointed governor of Germania in 7 AD and led three legions along with nine small auxiliary units against Arminius.
The battle occurred on the morning of the 7th of September 9 AD when the Roman army mustered to move out. The main fighting took place over two days starting that morning before the Romans were trapped near Kalkriese Hill.
Archaeological evidence identifies the battlefield at Kalkriese village which is part of Bramsche in Lower Saxony north of Osnabrück. Excavations since 1987 revealed debris along a corridor almost 3 kilometers long between woods and swampland edge of Great Bog.
Logistical challenges prevented armies from being supplied via the Elbe river due to hazardous Atlantic seas and extensive overland routes. Economic analysis showed the Rhine region supported towns and villages better than Germania Magna which lacked food surplus or tax base for conquest.
Estimated casualties ranged from 15,000 to 20,000 dead among the Roman forces. Varus committed suicide while Legatus Numonius Vala was killed by Germanic cavalry and other commanders either surrendered or died leading doomed troops.