Short answers, pulled from the story.
General Michael Andreas Barclay de Tolly commanded the Russian First Army. He held deep reservations about fighting but decided to engage at Vitebsk due to political pressure from the Imperial Court.
Napoleon set his troops in motion at daybreak on the 27th of July 1812. The engagement lasted several hours while French artillery fired deadly salvos without breaking through the Russian lines.
The battlefield at Vitebsk was a vast flat plain separated by the river Dvina. General Peter Graf von der Pahlen led the rearguard that remained to delay action on this terrain.
Napoleon stopped his attack early because he was unwilling to risk high losses against vastly outnumbered forces. He failed to press General Peter Graf von der Pahlen hard enough to render the retreat difficult for the Russians.
Riehn estimates 400 killed, 900 wounded and 70 captured for the French side. Colonel Liédot died in action as commander of the army's military engineer corps general staff during the fighting.