About the light placement. You can right click to select and then use the red/blue/green manipulator to move it along the x.y.z axis or you can hit g(grab) and move it around with the mouse. The later requires you rotate the view to a position that will allow you to do this affectively. Using the numpad period key will pull you over to the light and let you rotate around it for better position. As for the tool menu T should bring it up. N key brings up the properties panel. It can be useful. as for the panels going missing, Ive had that happen. If nothing else save the scene reload the start up scene and append the scene with the wacky interface. This will bring your geometry in with out the messed up interface.

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"The true sign of intelligence is not knowledge but imagination".

Albert Einstein