Explanation for the ending of Super 8

Question

Can someone explain the ending of Super 8 to me by helping out with the following queries?

1. What caused all the metal to be attracted towards the water tower?
2. Why in the world did the military leave the cubes lying around in the town even when they knew that the alien was there?
3. What was the Alien creating underground?
4. What did he need all the people for (the ones he keeps underground)?
5. How did the alien recreate the ship?

Answer 1

1. He might have built some sort of a large electromagnet in order to attract all the cubes, although I doubt that the child's necklace was entirely made of iron). The engines he stole from the cars were supposed to provide the needed power(maybe a giant electric current generator).
2. This probably happened because of their ignorance and self confidence: they always underestimate the alien and think of it more as a beast(remember they are soldiers, not scientists and they seem to be of the shoot-first-ask-questions-later type).
3. The alien was trying to rebuild it's ship in order to go back home.
4. He was eating them. He was not eating humans at first, but after so many years of imprisonment and torture, he began hating the whole human race. By eating people he fed himself and also got a feeling of revenge.(This is somehow stated by the children when they get into the lair).
5. He probably knew a few things about the way the ship was working. What is more, those cubes seemed to be like pieces from a puzzle, the alien only lacked the "glue" to piece them all together. Probably it was some kind of magnetic field, hence the answer to question 1.

Answer 2

I am going to answer all your question per my memory and I think all of answers are in the movie itself -

1. The alien has created a device from the various stolen electronics attached to the base of the tower which makes metal devices attracted towards the water tower. Alien doesn't want to attract metal but wants to collect all his cubes.

2. Military didn't leave the cubes around in the town but they are trying to research on the cubes' technology and the train crash is the reason for the cubes to be distributed in town but still most of the cubes are still with the Military.

3. Alien is trying to create a device which act as a magnet to attract his cubes from all around the town.

4. I didn't get the 4th question, so I am not able to answer it.

5. The cubes are all responsible in making his ship, it's like if the alien has all of the pieces of cube he can easily make a ship.