One of your questions was about the burning of Barnesville. This is from "The History of the 13th Illinois Cavalry by Major Frederick Behlendorf.

On August 7th 1862 we saddled up and made a raid to Van Buren to meet Coffee's gang, which we did, charging and routing them, with a loss of 2 killed, 5 wounded and and 16 prisoners on the Rebel side. All their arms were broken up and the town of Van Buren set afire and burned to the ground, this being a regular rebel headquarters. Shortly after our return to Greenville we went on another raid to Barnesville, scattering the rebels wherever found and burning the town of Barnesville likewise for the same reasons already given.

I would say in the month of Aug 1862

Jack