By the end of the second part of the story, we know that Farquhar unsuccessfully attempted to torch Owl Creek Bridge. We also know that he did that in an attempt to serve the Confederate cause. Though the narrator informs us that Farquhar "chafe[s] under the inglorious restraint" (2.1) of being a civilian, it is his decision and attempt to burn down the bridge that proves he is dedicated to serving the Confederate cause. Whether or not his decision makes him a hero or a villain is up to you.
As a southern plantation owner, Farquhar is also a slave owner. We never see Farquhar with his slaves and don't know how many he owns, but we know he is a willing and enthusiastic participant in the institution of slavery. Descended from "an old and highly respected Alabama family" (2.1), Farquhar most likely lives on the family plantation and owns slaves his father owned before him. These details allow us to know quite a bit about Farquhar. He treats human beings like livestock, buying and selling them, and making them work for no pay.
Farquhar is also wealthy. The Civil War was often called a "rich man's war and a poor man's fight." Though historians have proven this isn't statistically valid, rich men could buy substitutes for themselves to avoid the draft. We know that Farquhar is not suited to be a soldier because of his temperament. A wealthy plantation owner might not be happy taking orders from a middle-class officer.