Muggles' Guide to Harry Potter/Magic/Werewolf

Overview
Werewolves are humans who, when exposed to the full moon, transform into savage, wolf-like creatures.

Extended Description
To become a werewolf, a person must be bitten by another werewolf. When the person transforms, they lose control of themselves and are not responsible for their actions. However, there is a potion, the recently discovered Wolfsbane Potion, which, if taken daily in the week preceding the full moon, will cause the victim to be able to keep their mind while they transform. They are then able to control their actions, and are virtually harmless.

One of the major characters in the Harry Potter Series, Remus Lupin, is a werewolf.

Fenrir Greyback is another werewolf who is mentioned in Harry Potter and the Half-Blood Prince. He accompanies the Death Eaters in the tower battle at Hogwarts at the end of that book, and attacks Bill Weasley in that battle. We also see him heading up a gang of Snatchers in Harry Potter and the Deathly Hallows, and fighting alongside the Death Eaters in the final battle in that book.

When Harry and the Weasley family are visiting Mr. Weasley at St. Mungo's Hospital after the snake attacks him in Harry Potter and the Order of the Phoenix, they ask what is wrong with a man in the ward who looks fine. Mr. Weasley quietly says that he was bitten by a werewolf, and is now upset because his life is ruined. When Mr. Weasley had mentioned that he had a friend who was a werewolf and was able to live an almost normal life, the man had threatened to bite him. During a later visit, Remus Lupin goes over to talk to him; we don't hear their conversation.

Analysis
Much prejudice against werewolves is witnessed throughout the series. In the wizarding community, werewolves are distrusted and even hated. Most people refuse to associate with them. We see three ways that wizards deal with this issue. When a person is bitten by a werewolf, they often despair and deem themselves doomed to be outcast; this is how Mr. Weasley's unnamed ward-mate seems to be reacting to his ailment. Remus Lupin, conversely, does what he can to make the best of his admittedly rough situation, either locking himself up or taking a possibly expensive and distasteful potion to render himself harmless. Greyback, apparently, chooses an opposite course, reflecting the distrust that he receives from wizards back at them as hatred, and emphasizing his fear-induced separation from the Wizarding world by deliberately Transforming in areas where he can do the most damage to wizards. We are told that Lupin became a werewolf after being bitten by Greyback as a child.

Questions

 * 1) If a human becomes a werewolf only when bitten by another werewolf, how did the first werewolf come into existence?
 * 2) Can a werewolf change at will, apart from when it is exposed to the full moon?
 * 3) When werewolves are mentioned as dangerous creatures, how would they be dangerous when not in transformed state as they transform only in exposure of the full moon?
 * 4) If Animagi in animal form are unaffected by werewolf transformation, why isn't there mention of a werewolf becoming an Animagus to avoid this transformation?
 * 5) Could a Muggle become a werewolf?
 * 6) Is it possible that werewolves are not victims of a "bad curse", but a legitimate virus that is spread through contact between saliva and blood?
 * 7) Could female werewolves bear healthy children?

Greater Picture
We never see a female werewolf, so the question of whether a female werewolf can bear unaffected children is not answered. However, we do know that male werewolves can father normal children; Lupin, a werewolf, marries Tonks, and they have a child together. The child, Teddy, has apparently inherited his mother's Metamorphmagus ability, but apparently is not a Werewolf.