bah i don't get why your asking so much about, almost all the questions were answered in the manga/anime. Aizen wants to be king, which is god, ruler of all spirits. To become god/king he needs ou-ken, to get to the throne of god/king, where he will kill god/king and take his place. He needs the hougoukyo to make the key, and the espada to rpotect him from the gotei 13 while he does it. He needs the houghoukyou to make the espada, but since he's forcing it to be "awake" , it takes damage, which he needs inoue to repair.
and the king probably isn't evil, since yamamoto said the recipe calls for 1 million "modsouls" the original key was probably created with the mod souls they use to replace them in their gigai's, considerably less evil, or maybe they used the quincy or sumthing.
"Knowing is not enough, we must apply.
Willing is not enough, we must do."
- Bruce lee