I've got to agree with John F. IMO you will save very little, if any money by the time you have paid P&P, VAT & import duty.
To add to the 5% import duty figure, if the cam has DV-in enabled (and possibly AV as well) then the import duty is calculated on the cam as being a VCR. This means the duty is higher (but I'm not sure by how much) and therefore the savings even less.
AFAIK most cam power supplies will work on any voltage and therefore all you should need to do is change the plug to fit a UK power socket.
I'm not sure of any cams that can be switched between PAL & NTSC so don't bank on this being an option. You will not be able to copy from the cam to a standard UK VCR. Even if the VCR can play NTSC it wil not record NTSC. You could make DVD's etc, but these will still be in NTSC unless you convert the files which will result in some loss of quality.
As already stated the analogue inputs on a USA cam will be NTSC only and therefore if feeding them with a PAL signal you will at best get a B&W picture. At worst it just wont work at all.
Mark.