Another Ottawa unicyclist? Awesome. Winter isn’t the best time for riding, but we do have a small community that does some trials and MUni rides during the warmer months.
If you have facebook, join the Ottawa Unicyclists group. That’s how we usually keep in touch.
They don’t salt the sidewalks–residents are responsible for shoveling the sidewalks in front of their houses. I don’t usually ride on the sidewalks. Instead, I stick to the less traveled roads and the bikepaths (which are conveniently plowed). I bike (or uni, now) all year 'round, so I do go out when it’s even -25 C, but I can’t say it’s much fun at that point. 
I did join, but under a different name and email (I’m Les Taylor). I refuse to have a facebook, but since that’s my only choice I’ve decided that my best choice is to hide from everyone. I hear there’s a real website on the way though, can’t wait for that :D.