You will get a PAL Magic Pack unless you specify in your reply to their "soon to come with totals" e-mail that you want an NTSC machine. Now I'm not sure if they carry both PAL and NTSC genuine unopened units, but if they have only PAL (which I suspect) then they will have to open it up and replace the motherboard with an NTSC one, which they have in stock available separately, and also possibly replace the euro keyboard (German, UK, French, or whatever it is) with one that has US kaps.
This would be a bit of a rape to the genuine new feel of the package, but it will look brand new, nevertheless. You can tell if the warranty sticker has been tampered if they opened it or not, upon receival. :-)
As for customs fees, yes they will be applied when the package is delivered. There is a slight possibility that it slips through undetected, however not likely.