I cannot say how useful this forum is, thank you all!
After solving the bigger problems, now I am stuck with the rotation issue. Normally in OpenSesame, I can assign numbers to rotation variable in the loop and simply put it in the sketchpad. It works smoothly. However, when I try to do it on OSWeb, rotation function doesn't work. I just wanted to ask whether it is not supported, or there is something wrong with my script. And here is how my loop and sketchpad script look like:
Thank you for your support!