Good for you picking up python and arcpy. I took a class in grad school in python and arcpy and have used that same book myself before. I didn't get too comfortable with it though til I found real applications for its use where I work and its been quite the timesaver for me.
Now to your questions.
You are getting the base name property of the raster but not an extension(file type). Your output from Copy Raster will need a file type or it will default to a GRID file which has a 13 character limit and limits the character types that can be in the name. This is likely causing your issue.
Also when joining paths and file names, I recommend using the os module and os.path.join to combine your path and name instead of concatenation.
https://docs.python.org/2/library/os.path.html