Hi there,
I dunnoo if this is where you found CMU’s level editor, though I can tell you that the most recent version I know of is here:
you can find one of the most recent level editor here
One of the reasons you had trouble finding it is that it’s still under development (though keep in mind under development and unusable are two completely different things, in fact a lot of it is just finding bugs, so if you do find any be sure to let us know 
)
Now on to your issues running the code,
the following import lines should fix all problems for you, simply put them at the very top of your file that you’re running
import direct.directbase.DirectStart
from direct.showbase.DirectObject import DirectObject
from pandac.PandaModules import *note that the “pandac.PandaModules import *” line will cause your load times to be huge, (about a minute, or less) so if you want to speed up load times a bit, simply look at your errors like for instance:
NameError: name 'LightAttrib' is not defined simply means that you should import LightAttrib, the “pandac.PandaModules import *” will import every panda module, basically, (except for DirectStart and DirectObject, which are the two lines I gave you above )
in the case of the error above you would put
from pandac.PandaModules import LightAttribsimply changing adding that line multiple times until python stops complaining that you’re missing things, and then your loads times will be uber fast
Otherwise I’d suggest the simple and easy fix
from pandac.PandaModules import *that takes care of like 70% of panda’s modules for you, keep in mind that it is loading 70% of panda’s modules though, so load times can become hectic, okay?
Good luck!