Weaknesses
Silver. Plain and simple. Silver is about as effective as fire, only it doesn't spread. Otherwise, any weapon will do but the wounds heal very quickly. A few minutes to an hour to a few days dependent on the severity of the wound.
Around Witches
First of all, werewolves can't tell witches from normal humans. After a little while, they can pick up subtle clues that alert them but it could take anywhere from half an hour to a month.
Werewolves regard witches as freaks of nature. Some find comfort in creatures doomed like themselves, but most find them repulsive. However, werewolves are smart enough not to provoke witches because they don't have the right sort of power to defend themselves.
Around Vampires
Werewolves despise vampires. The reasoning for this war is long gone, but if one runs across another with no (or sometimes even just a few)witnesses then a fight will ensue. It is something that comes naturally with the blood of vampires or genes of werewolves.
Abilities
Newborns and weaklings need the full moon to gather enough energy to transform, a process that takes only a few seconds unless injured. The old and the strong need nothing. In their human form, werewolves have slightly stronger senses than humans and always have the very high sense of smell of the wolf. Generally stronger and faster than humans. In their wolf forms, they're faster and stronger than any normal wolves.