I rifle hunt in Ontario each year and own property there so cross many times. You do have to register rifles & shotguns, not a big deal. Handguns, forget it.
I also carry a recurve bow & judos, for stump shooting. When I'm crossing with just the bow & judos, I tell them when they ask if I have any weapons and they don't care about it at all as it's not on a list of weapons to register. So no problem getting it in.
As far as shooting it, if you're at a fishing camp and "flinging a few arrows" right at the camp and not roaming thru the woods, I'd not be concerned about a tag. Best advice I can think of is to call your outfitter and ask their opinion. I buy a small game tag late summer because I bowhunt & shotgun hunt partridge later anyway. But I also shoot my bow around my camp earlier in the year and am not concerned about that even without a tag, but this is my own property & I'm pretty obviously just practicing in my old field. When I start stump shooting in the woods, I like to have a tag with me.
Have a great trip, a good Canada fishing trip is truly a wonderful experience.