Sorry for the late reply. my barrel was 53 gallons. I used an airlock, although I had to add to it a few times as the levels drop (both the beer and the airlock), so I'm assuming it pulled some in to the barrel.
If you're going to drill the bug to make an airlock, you won't want the shavings entering your barrel. pull it out and drill it, then reinsert it.
I was advised not to use hot water on my barrel as it would strip too much of the flavors of the bourbon barrel, but if you don't want wood/bourbon/wine flavoring, then it would be a good way to rinse, and help swell the barrel. I poured a 750ML Bottle of Canadian club in to my barrel and rotate and moved it around for two days to make sure I had good coverage. I drained it out, and only ended with about 500ML, so I guess the barrel was "thirsty".
by the way, teh beer is delicious. I've tapped the first keg on beer gas through a nitro faucet. I've already been asked about getting another barrel to do it over again. I need some bigger fermenters and do larger batch sizes to make it worthwhile.