Focus accuracy with green hexagon is not accurate; there will be a range in which the heaxgon will indicate that focus is achieved. The truth is somewhere in the middle
With lots of practice you can probably get used to the behaviour, but if you're a fan of very shallow dof, I would not rely on the hexagon. You can opt for a third party split prism screen (e.g. katzeye or jinfinance) as a focusing aid; there was also a thread about the EE screen.
I can not really judge metering; if I get it wrong, I retake it or adjust in post processing.
ps I use a K100D with focusing screen if I really want the accuracy. On the K5 I rely on a mix of dof, what I see in the viewfinder and the hexagon with reasonable success