No. The orientation settings affect the application AndroidManifest.xml file. This file describes the application for the OS. One of the parameters is the orientation mode. Therefore it must be done during compilation.
This is a different question. Each time an orientation change occurs the activity is recreated. You can check the orientation in Activity_Create with Activity.Height / Width or with GetDeviceLayout.
See this post for the recommended way for handling multiple layouts: http://www.b4x.com/forum/basic4andr...2-guess-my-number-visual-designer-events.html