TBH I doubt £700 will get you all the things you have listed!
Good low light performance means having a bigger lens & CCD(s) and these cost money and therefore tend to be found on prosumer cams.
DV-in & AV-in are also only found on the more expensive cams as the EU class a camcorder with any inputs other than just the lens as a VCR and therefore more tax is payable
I think 16x optical zoom will be a waiste as even on a fairly good tripod at full zoom you will still get camera shake. Without a tripod it will be totally unwatchable, even with steady shot on the cam.
Perhaps going second hand may get you more for your money!
Good luck with your search,
Mark.