Hi,
I did this wonderful trip last November. It was seriously cold at -31C degrees! Somewhere on the Forum I have advised on what clothing to take - I thought I had gone over the top with what I took, but no, I hadn't! I took a North Face Arctic Parka, Sorel boots (which are fantastic in the snow and ice and which Yvette the Tour Manager was also wearing!), Icebreaker thermals (in different weights), two pairs of thermal gloves, fleece hat (I had to buy another one in Churchill - rabbit fur with ear flaps!), merano wool scarf (Buff), ski trousers, thermal socks etc. etc. You cannot be too warm!
I too did the Toronto add-on but I actually extended my stay to stay with family for 10 days. I actually found Canada quite expensive, but I guess you can eat/do things cheaper than I did!
Enjoy and have a fantastic time!
Cheers,
Hils