First things first, welcome to the forums.
I have a couple of these switches.
In answer to your question I don't think they can be told to come on to a certain %. Although they do remember the last level setting and come on to that level again. I taught my switch to take a signal from an unused button on a tv remote. If you tap the button on the remote the light comes on to the last light level. If you hold the button the lights will dim and brighten - you then release the button when the desired level is reached.
The sensor appears to be quite responsive from acute angles, although that may just be due to the power output from the remote I am using.
Hope this helps.
Sheks