Yes. Apple will charge $99 to repair a phone screen. If you try to do it yourself, the cost of the parts and tools will be about $40. So, it's worth repairing a phone screen.

It depends on how big the crack is and how much it affects your ability to use the phone. If it's a small crack and it doesn't affect your ability to see or use the phone, then there's no need to repair it. But if the crack is big and affects your ability to see or use the phone, then you should repair it.