Hello,
Regarding original functionality of mouse button when disabled key is pressed - this works for me, could you please describe the exact steps to reproduce?
Regarding the second - this sounds like a good idea, like using ESC key to revert to original scrolling point, right? But what do you mean by outside of range?
Please contact me either on my support email or create a bugreport directly here:
https://github.com/fastaddons/ScrollAnywhere/issues
Thanks!

Best regards,
Juraj Mäsiar