I’m rotating a rectangle with a slider… but instead of turning smoothly, it spins wildly out of control. What’s happening?

I’m trying to loft between these two curves, but the surface comes out twisted (see the red X). What’s the real issue here? How would you fix it?

I want this rectangle to be drawn from its center, but it’s drawn from the bottom-left corner. What’s the most likely issue? Please vote, then explain your reasoning :)

I’m evaluating this curve at 0.5, but the white “point on curve” and the blue evaluated point don’t coincide. What’s the most likely cause? Vote, then explain your reasoning in the comments.

I wanted to draw a line between the points shown in the screenshot. But in the viewport, it looks like there is no line? What’s wrong? Can you figure out why and how to fix it? Join the poll and share your idea in the comments!