You definitely made the most of the 5 points that would be deducted to you by asking a question! This is quite a tall order!
You're the nth person to have asked the first 2 questions, but I'd answer them nonetheless.
Harry was given the choice to either "go on" or go back because his decision to sacrifice himself to save others made all the difference in dying and living. He was able to conquer death by not being afraid to die. Voldemort only killed his own bit of soul that was unintentionally put into Harry.
Neville got the Sword of Gryffindor because he displayed bravery and daringness. Griphook's claim that Godric stole the Sword for Ragnook was not true. Gryffindor is the true owner of the Sword (and the Sorting Hat, too) and since he's considered a great wizard of the age, he would have put advanced magic and enchantments on the Sword that goes beyond whatever Goblins' idea of ownership is or mere physical possession of it. It was just like when Harry was able to pull it out of the Sorting Hat, it was securely hung at Dumbledore's office, yet it was there when he needed it.
Voldemort performed Dark Magic on Peverell's ring, just like he did with the locket. Dumbledore, on his desire to see his parents and sister, put on the ring, forgetting that it was already a Horcrux and thus, would be cursed. Snape was able to contain the poision on his one hand (that's why it's blackened) and control the spread of the poision for the time being.
Fleur was the Beauxbaton champion during the Triwizard Tournament. She and Bill met at Hogwarts by then end of the book, decided to work at Gringotts to improve her "eenglish" and Bill became her "tutor".
Tonks was an Auror who was introduced in the Order of the Phoenix. She was one of Harry's guards when they rescued him at Privet Drive to the Order's Headquarters. In book 6, she was in love with Lupin who didn't want to pursue any relationship with her because of his condition. She is a niece of Bellatrix and Narcissa (her mother Andromeda was their sister)
Percy the big-time-careerist-prat had a falling out with his family in book 5 when he decided not to believe Harry and Dumbledore (and disowned his family for doing so) and instead put his loyalty to Fudge and the Ministry.
Mundungus Fletcher was a low-life petty criminal, who was a member of the Order of the Phoenix. It was because of him that Harry and Dudley were attacked by the Dementors. He left his post as Harry's guard to look into cheap cauldrons he could buy then resell.
Mad-Eye (Alastor Moody) was a brilliant and very skilled Auror, and member of the Order of the Phoenix. The real Mad-Eye did not become DADA professor, it was Barty Crouch Jr impersonating Moody.
Hope this helps.