Tim,
No I don't believe the winter pack is standard on any of the models, as I've seen plenty of Ed30's and Pirelli's without headlight washers, which are indeed part of the winter pack combination.
My vehicle had the winter pack from factory and came with the four items you mentioned in your second paragraph. Heated seats certainly are not standard, as I've been in MK5 GTI's of all model/engine types both with leather and cloth interlagos seats, some with heated, many
not.
Not sure regarding the heated mirrors being standard in all honesty, I've not really taken notice.
Re. the arm rest stuff, none of that is affected by having the winter pack. I think the 'Lux' or luxury pack decides what you may have here, plus other extras like the MDI interface and other arm rest options which I think are individually specc'ed
If your car has Xenons, it would have headlight washers anyway (if factory fitted, presumably so).
The fact your car has heated seats would suggest you do have the winter pack, and the owner from new specc'ed the Xenons as an option also alongside the Winter pack.