import arcpy
arcpy.AddMessage("howdy") # just for debugging--writes to arcpy console

#Set Global Variables
mxd = arcpy.mapping.MapDocument("CURRENT")
df = arcpy.mapping.ListDataFrames(mxd, '')[0]
# create a new layer
newlayer = arcpy.mapping.Layer(arcpy.GetParameterAsText(0))

# add the layer to the map at the bottom of the TOC in data frame 0
arcpy.mapping.AddLayer(df, newlayer,"BOTTOM")
ext = newlayer.getExtent()
df.extent = ext

#Refresh Table of Contents
arcpy.RefreshTOC()
#Refresh Active View
arcpy.RefreshActiveView()
#sys.exit(0)

# get information about a layer
desc = arcpy.Describe(newlayer)
arcpy.AddMessage("For the layer " + arcpy.GetParameterAsText(0))
arcpy.AddMessage("The following properties were returned from arcpy.Describe():") 
arcpy.AddMessage("The file name is " + desc.file)
arcpy.AddMessage("The path from Arcpy.Describe is " + desc.path) 
arcpy.AddMessage("The element type is " + desc.dataElementType)
arcpy.AddMessage("The file extension is " + desc.extension)
arcpy.AddMessage("The data element type is " + desc.dataElementType)