1) is the galaxy actually smooth- the unit i played with in the shop was worse than my hero in terms of smoothness. It really disappointed considering the technical specs of the processor etc
Mine is certainly smooth. I would imagine that the one in the shop has been played with a lot and therefore has tons of apps open and is therefore running low on memory. Any app killer will sort that out.
I find mine just as fast as an iphone.

May be worth doing a full backup and ticking 'repartition' in odin. I too was having stuttering/stalling issues with the stock firmware and JG1, but for me they're almost non-existant with JG3.