A full calculation is found in this point at wikipedia.
However the jest of the topic there is that the center of gravity needs to be in front of some point "neutral point", which is based on the lift of both the tail and wing.
A canard type craft can never be stable, so you constantly have to correct.
It's important to realize that stability is important, but one can fly without stability. An unstable craft is like balancing a pencil on your fingers: you constantly have to correct. Luckily we have something called "computers" - or "SAS" in ksp that can correct this to a certain point. If sas won't be able to, you probably also won't be and you'll have to increase the control surface volume (area * distance from center of mass).
I have never ever anyone use "negative angle of attack" (or negative lift when horizontal for that matter) so I can't talk about that. If you mean negative cl-alpha: well that's impossible even a simple plate has a positive cl-alpha coefficient.
Static jaw stability is reached simply by having a larger (non moving) vertical lifting surface behind the center of mass. Just like longitudinal stability, it's just easy since there is no main wing. Further stability can be achieved by giving dihedral (in case of wings below body) or anhedral (when wings are above the body) to the main wing.
If it's dynamically unstable it is probably causing a dutch roll. A combination of yaw and rolling movement. This is a particularly nasty eigenmotion as improving dutch roll stability reduces the spiral stability (and vice versa). Some aircraft (cessna citation) even opted to go for unstable spiral motion in favour of keeping dutch roll stable. The cause is that when ailerons increase a rolling motion one of them has more drag, thus creating a yaw effect (adverse yaw). The yawing motion (correction) causes a rolling motion as the angle of one wing more perpendicular to the airflow than the other.
Dutch roll can be reduced by putting the wings below the center of gravity, reducing dihedral angle and reducing wing sweep.
