Howdy
You did pull the wedge almost all the way out to free the barrel, right?
Try using the loading lever as a ram to pull the barrel off. Place the cylinder so the web between two chambers is under the ram and use the leverage of the loading lever to push the barrel off. Be gentle, don't overdo it. There are two pins set into the frame, and there are two holes in the barrel that fit over the pins. If the barrel is rusted onto those pins, it can be difficult removing the barrel. The last thing you want to do is to pull the pins out of the frame. If the barrel is still stubborn, try some penetrating fluid between the frame and the barrel.
Forget about vinegar, it will remove the blue on the steel.
Once you have the gun apart scrub everything with hot soap and water to remove the old BP fouling. When everything is clean and BONE DRY, coat everything with a light coating of Ballistol to prevent rust and put everything back together again.
Forget about trying to keep the brass frame shiny, it will just tarnish again, and you may overdo it with your polishing.