It's normally spelt 'craic' when speaking about the word that means something like fun/banter/having a good time which is commonly used in Ireland. We know this word in the rest of the UK, at least passively.
I have some friends from Ireland, and I've never heard them use that word to mean beer before. I'm not sure if that's right. Perhaps someone from Ireland can corroborate. I've heard them use 'craic' plenty of times though.
e.g.
Do you want to go? Should be good craic...
It was great craic last night,,,
What's the craic? (I had a friend who used this all the time, it means something like 'What's up? or 'How it's going?')
'Crack' has lots of potential meanings, one of which is drug related, yes. Crack cocaine is a type of illegal drug, which is commonly abbreviated to 'crack.'
I'm not convinced that sentence means 'Do you want to go for a beer?' Certainly no one would interpret it that way in the UK.