It seems more likely that Canada has suffered no terrorist attacks because it is not the international hegemon that the US is. It's not as if the US was oppressing Muslims here in our country before 9/11.
As to the question of the Bill of Rights, there is always a balance between civil liberties and order. We never have the complete right to free speech (we can't threaten others, for example). It is reasonable, in my mind, to shift the balance to some degree away from liberty and towards order in our current situation. This does not mean that we throw away all liberties, it means that we accept some reductions of liberty for our safety.
Of course, this is a slippery slope. It is very hard to know how much (if at all) our safety improves if we lose some of our rights so that the government can do more surveillance. We cannot set any bright line and know that that is exactly how much in the way of rights we can afford to lose.
In theory, it makes sense to have our rights restricted. In practice, it is very hard to know how much restriction to accept.