Concerning the switch back from monitor mode after a couple of seconds for some Samsung SPF I have found on "http://pyframe.blogspot.de/2011_12_01_archive.html" this information (it's from a python script).
# This control function is required to keep the frame permanently in Mini Monitor mode.
# When the frame is switched to Mini Monitor mode, it remains there for a few seconds, but
# then switches back, unregistering from the USB bus.
# This function is needed only once after connection of the frame, but it does not seem
# to do any harm when transfered with every picture t