Why would he have to ask?? ..... and then willingly be lead into Temptation
The temptation is there regardless. Jesus's request was for God to help people resist Satan's temptation. "and deliver them from the wicked one"
he casts the ultimate tempter to the vicinity of the earth... so he can do it as much as possible...
Nothing to do with him being able to do it as much as possible. There is no difference between Satan having access to heaven and then being cast out and no longer having access. Satan can tempt the same wherever he is. Revelation says woe for the earth because of Satan's anger because he knows his days are numbered, not because he is in the vicinity of the earth.
The issue which started this whole process of temptation etc. was the question whether mankind could live successfully independent of God. And could humans remain faithful to God despite Satan.