There aren't too many rules to adhere to. You'll need an officiant and you'll need signatures, but outside of that anything goes. Help each other getting ready? Why not. Exchange vows before the ceremony? Why not. Keep things simple and focus on the celebration. Focus on what makes you happy.
I've only visited Halifax's Waegwoltic Club during the summer months - this was the first time I've been there during the winter. Old buildings decorated for the holidays have an endless amount of character and warmth - those present only added to it. This wedding serves as proof that a winter celebration can be just as rewarding as one held during the peak of summer. Enjoy!