Few questions about skinning, specifically in Cata

So as a Worgen druid with dark moon fire water, is 40% deftness the most i can go? That put me at a 1 second skin when I was Farming baby crocs. I thought I seen somewhere that worgen skinners were at .5 seconds. Also, why does my skinning go up to 1.5 seconds when I go into Firelands?