Short answers, pulled from the story.
The Italian garrison surrendered on the 22nd of January 1941 after a fortnight-long blockade. General Enrico Pitassi Mannella commanded the XXII Corps that was defeated by Allied forces.
Erwin Rommel advanced with the Deutsches Afrikakorps and ordered the investment of the port on the 10th of April 1941. Heinrich von Prittwitz und Gaffron commanded reconnaissance units sent to block the eastern exit from Tobruk.
By the end of April, virtually all Tobruk-based fighters had been removed from the encircled port. On the 1st of May 1941, 274 Squadron lost all six Hurricanes it sent on a single mission when engaged by Bf 109s led by Gerhard Homuth.
Only 30 tanks remained operational at the end of the 15th of June during Operation Battleaxe. The operation resulted in 1,000 casualties and reduced the Allied force to just 10 tanks before they evaded encirclement.
Operation Crusader began on the 18th of November 1941 with an outflanking movement bringing the Eighth Army within 16 kilometers of the perimeter. The plan intended that the 70th Infantry Division would break out from Tobruk on the 21st of December to cut German lines of communication.