A noncreature permanent that turns into a creature can attack, and its {T} 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.
2008-08-01 • wotc
If X is 0, Chimeric Coils becomes a 0/0 creature and is put into its owner's graveyard.
2004-12-01 • wotc