Nikon Adapter for m43

Hi All

Just got my E-M5 and really am loving it. I have two lenses the far for it but I'm kind of interested in playing around with my Nikon lenses. I have a 70-200mm f2.8 VR2 and would love to see that 400mm equiv. My questions:

1) I checked out a few Nikon F-mount adapters, can anyone recommend one over another?

2) I've never used any adapters on any camera. What will I be losing? I'm guessing I'll only be able to use manual focus? Does the camera still properly communicate with the lens to set aperture and such since many lenses do not have aperture rings anymore? (okay that's three but they all go together)

Thanks for any help!

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-A