2: John specifically and unnecessarily points out that Nathanael was from Cana. This refers back to Jesus' first miracle in chapter 2. Basically John is telling us with all of this that a new story is now beginning. This is the epilogue.
5: The fact this made any sense to call them children seems to me to point to the fact they were probably all very young men, maybe some of them in their teens.
7: Something tells me Jesus laughed when Peter did this.
11: Another one of those pieces of unnecessary information: 153 fish. John seems to remember the number quite well. - hey, he was there. If John had made this story up, to put this number here really would make no sense at all.
15-17: Three times Peter denied Christ, now Christ is having him affirm him three times. Each time Jesus is basically telling Peter that true love for Christ will express itself through a Pastor's heart for the Head Pastor's sheep.
19: Seems clear that the gospel was written after Peter's death. I love the final remark: "Follow me". This clearly implies forgiveness, because it is not just meant as a command, but as a privilege and offer being given to Peter. Peter must have been crushed by his guilt. But with Jesus calling him to simply follow him again, this is indirectly telling Peter that everything is forgiven.
23: Note how John does exegesis here for us and clearly tells us there are wrong interpretations of Jesus' words - in fact that some of the apostles had wrongly understood Jesus' saying about him.
24: Again, John repeats that this book is his own testimony. He wrote it, and its truthfulness is directly connected to his truthfulness. To doubt it is to accuse John of lying.