somewhere
It leads to the Twilight world of Hyrule where the spirit of each province has their light stolen and Link must go through the wall to get the tears of light back to the spirit.
You only have it in the twilight world so whenever you are in the twilight world you have the light sword.
You kill them
Usually you will be taken back to the spirit to bring light back to the area. then you need to work on getting to the temple or if you have a task before that work on that then you work on getting to the temple.
Light arrows were not placed in Link's possession in The Legend of Zelda: Twilight Princess because light arrows were not essential in Link's fight against Ganondorf.
The light spirets mark them with dots on your map.
No, there are no cheat codes in the game.
You do not get Light Arrows or Magic Power in Twilight Princess, so this would be a no.
steal or buy some from trill, buy some from coro, i guess at any store
no
You cannot 'lose' a Tear of Light. If you neglect to pick it up, it will remain marked on the map until you do so.
I think Link from twilight princess