The Battle Lines Drawn

Is the battle still ongoing? Is Satan able to harm the LORD's children? What is the significance of the number 40 in Scripture? Why did Christ enter His ministry at the age of 30? Is there connectivity between all of the Scriptures? Why did the LORD choose the serpent as the personification of Satan? Is Satan omniscient or omnipotent or omnipresent? Is there any room for compromise with the world and Satan and the flesh? What is the evidence of one that is on the opposite side of the battle from Christ? How is it that out of the heart the mouth speaks?