The letter W is since 2006 once again an official letter of the Swedish alphabet. Like Q and Z, it only turns up in loan words and some names. That’s why you won’t find a lot of Swedish words with a W in it.
W is always pronounced like [v] in Swedish; like a V.
English loan words are mostly pronounced in an English fashion. W could then be either mute or pronounced like [w] (half-vowel). The pronunciation is a bit individual and not written in stone.