Question #2: What about people born before Jesus?

Regardless of when you were born, Jesus remains the one and only sacrifice for sin. For those of us who live on this side of the cross, we place our faith in the finished work of Christ and what He did on the cross to pay for our sins and repair the separation between us and God. But for those who lived on the other side of the cross, they are still saved by faith. But their faith is different. From the time of the fall in the garden, God promised a day when He would deal with sin and Satan once and for all. The nation of Israel offered animal sacrifices for sin but knew that it could never fully atone for them. But God constantly promised them that a day was coming when He would send a Savior. Read Isaiah 53. Therefore, people in the time of the Old Testament were placing their faith in Jesus by believing the promise of God that the Messiah was coming. So when you read passages like Genesis 15:6 which says that Abraham believed God and it was credited to him as righteousness, you see that it is still by the same faith you and I have that Abraham also is justified and made right with God. His faith points forward toward the cross. Ours points back. You'll also find a great passage on this topic in Hebrews 11, especially notice verses 16 and 39-40.