STAR WARS: ATTACK OF THE CLONES: I'm confused...?

Who did the people of Kamino make the clone army for? I thought they said it was for the Galactic Republic, but Jango Fett doesn't seem like a good guy. Why would he help the Galactic Republic when he's bad? Why does everyone want to kill Senator Amidala? Was Jango Fett the one that gave orders to Zam Wessel to kill Amidala? First Count Dooku says he's against the Siths, but at the end of the movie he's with Darth Sidious. What's with that? Why did Darth Sidious sound pleased to hear that a war had been started. What is the Death Star and what does it do? Sorry for all the questions, I find Star Wars movies hard to follow. I have already watched the movie twice and I've read what Wikipedia had to say about it.