[FOSDEM] Beer event

Hello, I should now be buying my tickets to the event but I can't decide if I will participate on the beer event or not.. therefore what dates I should choose. How many people are usually showing up? From the descriptions I've read so far it seems that there are quite a few.. But the more important question is whether smoking is allowed in pubs in Belgium? I am personally a non-smoker and cannot really tolerate smoke, so if it is allowed then I am afraid I have a definitive choice.. I hope this wasn't asked before.. Thanks, Gabor