How to disable CMD + E to eject?
You can use Karabiner with a private.xml such as this:
<?xml version="1.0"?>
<root>
<item>
<name>Disable ⌘E</name>
<identifier>DisableCMDE</identifier>
<autogen>
__KeyToKey__
KeyCode::E, VK_COMMAND | ModifierFlag::NONE,
KeyCode::VK_NONE
</autogen>
</item>
</root>