Hi Mana!
:welcomewagon:
I agree that she looks like a standard Rex. I also raise Rex, and she is more than old enough to breed. If you are breeding for meat, any rabbit within a couple pounds of her weight will be fine.
We have two other members in Canada who breed Rex, and they do fine in your temperatures. Just make sure she is out of the wind and can't get wet.
If you move her outside once it gets warmer, she will be fine this coming winter.