When a creature is put into an opponent's graveyard from the battlefield, if Lurking Skirge is an enchantment, Lurking Skirge becomes a 3/2 Phyrexian Imp creature with flying.
A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn’t matter how long the permanent has been a creature.