Some of the defaults seem aimed at the newer users.
That colored ls is in your profile, .bash_profile if you took the defaults, or possibly .bashrc. You can always turn it off with ls --color=no.
As for me, I find they can be convenient, but not that green they use for executables, so I change that. I believe you copy /etc/DIR_COLORS to your $HOME directory, and then you can mess around with it. in a typical 24 line xterm, doing pgedown twice should get you to the part you'd want to change. Oh, in your $HOME directory, you call .dir_colors
HTH.