Jesus was praying to his Father concerning his life's work & purpose. He had done everything - finished everything he was given to do - next day he would die, & with his dying breath he would tell the world his work was finished.
Yes. And a week is divided into 7 days, when one day ends, the next begins. As the song put it:
"Today will be yesterday tomorrow."
Gabriel said "70 weeks" not, "350 weeks."
The first 7 weeks were concerned with the rebuilding, as recorded by Ezra, Nehemiah, Haggai, Zechariah & Malachi.
The 62 weeks are the intertestamental period up to the baptism/anointing of Jesus.
Note that v. begins, "And after the sixty-two weeks..." and from the Gospels we can read the events, & see that as a consequence of the rejection of Messiah, the city & sanctuary will be destroyed - after a period of desolations. Obviously AD 70.
Week 70 is Jesus' saving ministry, during which he was confirming the covenant, & in the midst of which he was cut off.
While there are 3 section to the 70 weeks, there is no suggestion that the 70th week is totally separate from the 69.