To what extent is the acceptance of repentance and the existence of hope possible, and is there expiation for the many broken vows, and what is the way to compensate for missed prayers?

One must not despair of God's mercy, no matter how great the sin, for God is Forgiving and Merciful, and His forgiveness is greater than any sin. Trust in God's pardon, have a good opinion of Him, and repent to Him with sincerity and devotion, for sincere repentance erases all sins. You must observe the obligatory duties, increase your supererogatory acts, and strive for uprightness.

The covenants you have broken are considered vows. Therefore, according to the Hanbalis, you are required to offer a single expiation for breaking them, as a تسهيل (facilitation). However, if you wish to be cautious, you may offer a separate expiation for each covenant. As for prayers intentionally missed, they must be made up according to the majority of scholars.