I am at the point in the campaign where you need to send Calisterre the Seer to infiltrate the military camp, either by the West, South, or East gate. I unlocked all the threats with red scrolls, she has an IMPOSSIBLE chance of finishing the mission at any gate but in a tutorial I saw they picked the south supposedly because she had a great chance, and I've reloaded and retried about 20 times. What am I missing, or is this game just trying to drive me insane?

Also in a tutorial I watched, the person was able to see exact percentages of her chance of success? But mine just says "impossible" or "improbable" etc. Is this a later update to the game?

I want to love this game but I'm ready to smash my laptop.

Just ignore what the game says. If I recall correctly I have send her through the south gate. You can train heroes using manekins, dart board etc. If you click on Calisterre there is tab when you can set on what skills she shoud be focused. Problem is that this tab resets itself each time you load/reload game.

I've finished campaign today so it is possible to finish it but my lord, there are lots of small bugs and glitches (e.g. in one of the final missions 'Pirate' did not appear so I had to reload game twice before I found out that if I not agree with Martin right away and decide to take some time to think the pirate will not appear later).