In the Greek temptation means to test or to make trial and may imply a probing to learn character and virtue (Gen. 22:1; Matt. 6:13; John 6:6), or to reveal weakness and evil (1 Cor. 7:5; Gal. 6:1). In respect to testing character and virtue it seems God is the source rather than Satan.
As to God's permission of evil, which is really what your second question boils down to, my answer is that God puts to test the theories of His creatures (Job 1:7-12). When all is said and done the mouths of those standing before the Great White Throne will have no recourse.
Clear distinction:
God tests, Satan tempts.
Look at Job's book.
With God's persmission, Satan did all those nasty things to Job, not God, God won't do anything "wrong" to his people.
God alowed that to happen because of more than one reasons.
Free will is one of the most important; God had to let man do as he wished -- even if that ment that man would fall from Him.