Your cavalry will be able to provide some intelligence, just keep working with it.
I do not play against AI, but you can tone it down a bit if that helps. AI is going to move for key victory locations with all its force.
You have thought of a great solution. You now just need a force/army equal to his.
It is not a bug. This is a relatively short duration option.
You have some tools to repair, those which help rebuild. So not a specific decision, but a lot of helpful decisions.
Traitor only appears once. Many cards can only be played once, then they are no longer available. Really powerful cards like traitor fit into this category. Others are limited, but renew after time.