Hi Golden Maven, you ask several questions.
1) How did Jesus know the Bible would be written? First of course, the Old Testament had already been written during the time of Jesus, He studied it and spoke of it and fulfilled prophecies in it. So your question really is, how did Jesus know the New Testament would be written? The short answer is Jesus knew it was God's plan and trusted that God would fulfill His plan. In John 17 we see where Jesus gave his disciples the word that God had given him, and then Jesus prayed for God to protect His disciples, not only for their sake, but also for the sake of those who would believe "through their word." Thus Jesus knew the plan.
2) How did Jesus know the original autographs, the handwritten writings of the authors or their scribes, would be "preserved without any modifications." I do not think Jesus knew or claimed this. I am unfamiliar with any scripture that makes this claim. What we know is that our scripture has been passed down to us and that it is remarkably close to what was contained in the original autographs.
3) How did He know His word, the gospel of Christ, would be translated into many languages and be carried worldwide? Again, He commanded his disciples to do just that.
4) Is the Bible complete? It is certainly sufficient. Is our understanding of His message complete? Probably not. Since there are different views, at least some of us have it wrong.
5) How do we know the Bible has not been corrupted so much that we cannot rely upon it? We know that at the time of Jesus, the Old Testament had not been corrupted too much, because Paul wrote that all scripture was profitable. And we know that at least some of the new testament, including the writings of Paul, were written and considered to accurately reflect Christ's word, according to Peter. And since we have copies that are within 50 years of some of those new testament writings, that does not leave room for wholesale corruption. Secondly, when you push back another 100 years or so, we can compare copies from diverse locations by diverse scribes, and they still say much the same thing. Thus we can have high confidence in the trustworthiness and reliability of the Bible.