Never had to do the 4457 on all the hunts I've been on in Canada. No one's ever asked.......
On the Canadian form that you are talking about, i'm assuming it's the Canadian Firearm Declaration form?
If it is, I got my butt chewed out a couple of times for filling it all out ahead of time and then signing it. Was told that i was not sign it unless it was in front of a customs officer. I never saw anything on the form that stated that, but that's what i was told.
On special office.........can't help you there. Flew in/out of Winnipeg, MB so cleared customs ahead of time so all we had to do when we landed was to pick up our rifles and leave.
On another note. When you return, you will most likely be brought to the back parking lot of the hotel to claim/pick up your meat and antlers/hides. There will be a meat processor and a taxidermist there if you want their service(s). I thought the meat processing was great and very reasonable. As far as the taxidermist (Pierre Gevry)........I would pass. Had him do one shoulder mount for me and i was not at all impressed. The mounts he had on display were great, but nothing like what i received. If you can get your hide and/or antlers back another way (checked baggage, etc.) i would try that route. On my last trip, i passed on the shoulder mount and instead had him clean the antlers, prep the hide, etc. and then had him ship it to me. Got gouged!!
I know someone that's going up to Leaf with a large group (whole camp) in a few weeks and he talked to Pierre about some prices. Prices went WAY UP!!
Could be another taxidermist there as well, but on both of my trips, Pierre was the only one.
Good luck and keep everyone posted.........they have Wi-Fi there!