I have a 2002 conti with a drivers side mirror (heated electrochromatic) that is so hazed over it is virtually unusable.

1) Can anything be done or is it f'ducked
2) Can the mirror itself be replaced?
3) Do I have to buy an entire assembly?
4) Good place to source used parts of this nature? (there are a couple on eBay but wrong color).

Yes, its toast.
Yes, the glass can be replaced separately.
Yes, while replacing the glass you CAN break the mounts and have to replace the whole assembly.
Get a NEW one from Ford. We have a resident FLM parts guy here with great discounts through the board. Free price quotes.