K5IIs & Sigma 30 f1.4 problems

Last night I just recieved my K5IIs and Sigma 30 f1.4. I notice the WB and exposure being off. I was using auto WB under cloudy skies and indoor lighting. With the Sigma 30 in matrix merering, the camera tends to over expose by about 1 stop sometimes. Thats the only lens I have currently. I also find that the center focus point is accurate but the rest I think front focus. Is this possible? Should I try the Pentax 43? Could it just be the lens? I was comparing the K5 to my D600 which is pretty good at WB and exp. But I love the feel of the K5 and its control layout.