Jackie - WOW!
I am one happy behaviourist!
Excellent job - keep it up....now if I can just sneak a few more little things in......
I am smiling - a LOT


Winter is a different problem altogether!
It is in her nature to herd, and along with this is the nip - but you do not have to and should not put up with this behaviour
This is not a breed quirk, it is a behaviour that is seen as acceptable by the dog because it is allowed.
Winter is pre -designed to use this as a strategy to get what she wants - it is up to you to decide if it works for her, is acceptable and if it continues.

Millions of collies, both working and non-working, live their whole lives without nipping. While it is a natural behaviour to her the only reason she keeps doing it is because it has some reward - it may be keeping strangers away from her, getting familiar people to do what she wants, getting positive feedback from the nipped person (high pitched squeals and fending off hands) or a hundred other things.
If you are happy with it then it can't be seen as a problem - if not, it can be stopped.
She sounds like a very clever dog and must be fun to have around - be aware though, that your breed is not a analysis of your dog.