Hi Anja - The answer to your first question may become more clear by reading the following thread: http://www.empirisoft.com/support/showthread.php?t=25

To answer your second question, you may want to look into how styles work with MediaLab. By using styles, you can more easily select how items are displayed. Quick styles can be used to switch between styles during an experiment. More information on these functions can be found here:
http://www.empirisoft.com/medialab/help/preferences.htm