The UniMap is a built in low resolution map of the U.S. (in Domestic units) and other maps in the other various International units that we build.
I believe that the 1197 units that we have been building since January 2010 all have the ContourXD maps in the U.S. version units. These are maps with some additional detail like depth contour lines on many of the lakes.
Yes you can still use a Navionics SD card regardless of which map set is installed in the unit. I don’t know what a 38XG card is but you can consult the Navionics web site to see if it is compatible or not.
All of the 1197 units we have built were shipped out with the GR50 50 channel GPS Receivers.