Well, um the shortest turn in Civ2 was 1 year

So, planning a war must of been done then.
My opinion on this (god I have so many!

) is that your people should be very important when considering war, especially in govs like Democracies. Obviously, you are not forced into listening to what your people say, but going against them can make life hard, riots etc.
Also, in reality wars mean spending money on armies, not only to conquer but to secure conquered cities...so units should definetly require money to maintain.
I think if trade routes are implemented properly, and are easy to set up, they could be a good deterant to war, like why destroy a civ who your getting 1000 gold per turn.