I have the last Redshift and it is getting a bit old now and will probably not be compatible with the LX50. As for starry night, I would contact them to find out, if no one else has the answer, that is.
The LX 50 and the Magellan I and II use a basic version of the Meade protocol they will display a set of cross hairs on most planetarium programs that will work with other versions of the Meade stable. however there will be no "goto" type command although some programs may be able to send the coords of an object to the Magellan II and then you can manually move the telescope to these coords.
You will need to have the correct cable connected to a COM1 or COM2 port at the correct speed. I think the speed on these may only be 2400 bauds. The details are in the manuals that are on the Meade site. If you only have a USB/RS232 adaptor you will probably need to configure it as COM1 or COM2.
