I can login to a lab Linux CLI, but have no further info on the install. Is there a generic command for starting a default DE/WM; I seem to recall startx would run a default X11 setup, but am looking to access a modern gui environment (if installed). Also, is there a default file explorer common to all distros? 
Starting a Linux desktop from CLI
linux;desktop
startx is still the standard way to run a desktop environment - graphical distros set up a desktop environment to be run when X is started. If it's not set up, you may want to look into creating your own .xinitrc.File managers are not distro specific; very few (if any) Linux programs are distro specific, since there's nothing fundamentally different between distros.