I am planning on aging a portion of a porter that I recently brewed in a 2.5 gallon american oak barrel that I purchased from Thousand Oaks Barrels. I was planning on adding about 8 oz of bourbon, swishing it around in the barrel for a few days, then adding the beer. (I already filled the barrel with warm water so the wood staves would swell closed). I was planning on leaving the beer in the barrel for about a month for it to barrel age. My questions are, do I need to add anything to the barrel besides the beer and bourbon? I am assuming that the Co2 will escape (along with some of the alcohol in the beer, do I need to top the barrel off from time to time for evaporation? what should I use to top if off? I am assuming that I can't serve the beer from the barrel since there is no way to carbonate the beer in the barrel? (Co2 would escape?, or if not then could I add malt extract/sugar to carbonate it?). The barrel does have an air lock. I was assuming you would only add yeast to the barrel if you were making a sour beer?