Questions about Byrd's successor

WV Gov. Joe Manchin faces a confusing set of rules when appointing a replacement for Sen. Byrd, writes Jonathan Allen in Politico:

Under West Virginia election law, Manchin surely would have been able to appoint someone to fill the entire remainder of Byrd’s term had Byrd died after July 3 – or with less than 30 months left to go on a term that expires Jan. 3, 2013. But with more than 30 months left of an “unexpired term,” the law stipulates that he tap an interim successor until an election can be held.

That law, however, isn’t clear on two points within the construct: First, the law is silent on when, exactly, a vacancy occurs – at the time of death, when the Senate informs the state or when the governor declares it? – and the law for calling a special election is written in a way that suggests that it couldn't be held until the date of the next regularly scheduled election in 2012.