To add a bit. Regular on licence is required for the sale of alcohol on the premises, as John said. The licence itself costs very little, the major cost is in persuading a publican to part with his existing licence. That's probably around €40k at the moment, down from €250k in the boom which is why all the new pubs built during the boom are of the mega variety.
The only organisation that has public policy on the tap room issue that I'm aware of is Renua, which you can find on their website.
Others may be working on a proposal that a restricted licence accompany a manufacturer's licence. E.g. permission to serve restricted hours, say 12 till 6 on Saturdays. (I think Renua's policy (for now) is a full licence be issued). Interestingly Northern Ireland's licensing was modified a few years ago and while simpler than in ROI, it's still nowhere close to the liberal licensing in England and Wales.
Under existing ROI legislation you can sell 4.5 gallons or more out the door (it's considered wholesale) for consumption off premises. It's an awkward amount and difficult to make it work.
I would say the ability to sell direct to the public in the brewery (i.e. taprooms) is the single biggest issue for Irish micros at the moment.
I wouldn't agree with John on his point about charging admission, but it is definitely not black and white.