I think a revisit to typical aerofoil section properties might be in order.
TE and LE devices work a little differently to each other.
TED tend to move the CL-alpha curve to the left, reducing the stalling angle without all that much variation in CLmax.
LED tend to extend the basic curve and increase CLmax and the stalling angle (important for jet takeoff, especially).
One of the problems is that it is easy to confuse body angle (ie ADI) with aerodynamic flow angles.