plane creation

I've created a plane that this perpendicular to a line in a sketch (had to use a mate connector to achieve this). However, for the lack of a better way to describe it, the secondary axis of the plane is not horizontal. I would like it horizontal so that I can use the horizontal constraint to ensure conformity with other…

I'm trying to write a feature script that takes a curve and a point as parameters (among others), and creates a plane with the x-axis pointing in the direction of that curve's tangent at the given point. (The motivation is, I want to then manually draw a sketch on that plane that extends the curve in some way.) Everything…