Thanks for contacting us. I've taken a look at your style and there are a few things you can do to help with those issues:
When I need curve splines, the roof gets stretched,
You can solve this using RailClone's curve steps option. It adds additional interpolation steps to smooth the base spline and consequently also the deformation of the segments.
when I use slope, the elements do not align.
This is a more complex issue that's caused by the mixing of deform modes. Adaptive mode's verticals follow the angle of the spline, bisecting the angle on the corners. On the other hand, Vertical and Stepped mode keep the verticals upright. If you mix these two modes they will be aligned correctly only where they meet on the spline, so if the bottom of the segments is sat on the spline, they will be aligned at that point.
One solution, therefore, could be to move the pivot for the objects to the top instead. In that way, they will align correctly where the join is visible.
Please see the attached file to see how this change looks on your style. Of course, the width across a bevel is wider than the normal cross section, but that's another issue! In the attached style I've solved this by resizing the corner segment based on the angle of the corner. For this I have used the built-in Find Hypoteneuse
I hope that helps, please let me know if you have any further questions.
All the best,