Yes you can. You do not necessarily need a confirmation if you are willing to take a small risk (and a vendor accepts risks much bigger than that if he's in business).
Considering the extent to which cigarette vendors around here keep their merchandise locked up, I don't think they're willing to take on a lot of "I hope these bitcoins are legit" risk.
Merchant software can listen to the network for 10 seconds. If no contradicting transactions have been broadcasted, the probability of the bitcoins not being legit is EXTREMELY small. You only need confirmations for large transactions. Zero-conf are completely safe for the large majority of transctions.
Bitcoin-type technology has tons of potential, my friend.
Credit cards are not a feature of a currency. You could just have credit cards that keep debt in BTC instead of USD.
The point of the person you're replying to is that, for 99.999999% of businesses, there is no benefit to using BTC. It doesn't offer the buyer any protection, it's extremely volatile, and it would require an overhaul of the entire economy's infrastructure to implement in any meaningful way.