I have an object that I cannot select nor manipulate. I can get into Edit Mode by using the Outliner however it is useless since I cannot Move it as an object. Seperating, duplicating etc the selection in edit mode doesn't do anything either.
See the icon that looks like an arrow next to the eye on the outliner?
If that icon is ghosted the object cannot be selected. Click on the icon to enable it
These icons are switches:
The Eye icon is to toggle object visibility on the 3D viewport.
The Arrow Icon toggles selectability.
The Camera Icon toggles rendering.
Please take a moment to read more on the Blender Manual