Hmmm I believe the devil is evil and has reign over those who are not God's. Scripture says that he walks to and from in the earth seeking who he may devour. Anyone who has been in the trenches knows that satan surely has lots of power here on earth. He can possess those who follow him, and those who give themselves over to his devices. (He cannot possess a Christian, and the Holy Spirit indwells them, and we all know God is stronger than satan.) Anyone who has been in the presence of someone who is possessed knows the power that satan or his evil angels give the person...much more than humanly possible alone. It takes the blood of Christ, and believing in it and declaring it, to overpower this evil.

No, satan didn't go to God to ask permission as we think of it, but as much to taunt God saying that GOD is protecting Job and not allowing anything bad to happen to him, and if GOD didn't protect him and allowed ill to come on him (Job) that Job would curse God and not be faithful. God said do what you will but you cannot kill Job. That also tells me that satan can kill, unless God stops him. The earth is satan's domain, according to the scripture. God will return and orchestrate the great battle (yes, war) called Armaggedon, and defeat satan once and for all.