hi,
1. visually import the stl files into the script is very simple to do.
visualization can be done using py openGL for example, or other method (many are available).
2. for collision check, you can use the AABB method (although it may be coarse, depending on your data) , GJK is a finer method, which may be more useful for your purposes.
3. the angle of the machine is a simple transformation of coordinates, i don't see any problem implementing it (also its only one rotation, so shouldn't be any "gimbal locks" or something like that)
using quatarnions or a transformation matrix should be fine.
4. I'll keep the code clean and annotated :)
5. I've seen the image, i think for simplicity fancy rendering should be kept as the lowest project priority.
thank you for reading.