Regarding Jesus descent into Hell, he went there to preach to the spirits in prison; the unbelievers from the beginning of time, when he made his promise of a savior, to his present.
Faith in the savior was as valid in old testament times as it is today. The difference being: they looked forward to the savior, we look backward at his arrival. Faith is the key. There are some instances of the value of old testament faith recorded in the epistles of Paul.
Nevertheless, Jesus' march was basically a victory march. He was showing those who hated him that he was victorious; that everything he ever promised or said was brought to perfect fulfillment.
His march in the streets of Hell is similar to an army of our times marching victoriously through the street of a conquered city.
Our savior's march through the kingdom of Satan is as encouraging and joyful an image as any heavenly image of him. He, to our comfort and encouragement, shows his domination over all things for our good, peace and supreme joy!
Wonderful!