Depth of Field

Hi A few questions......

Been reading on here lately about the optimum aperture on lenses is generally around F8 / F9 for best results / sharpness but this is confusing me somewhat as I thought that when say taking landscape shots using a smaller aperture say F16 would give you better depth of field (is depth of field the same as sharpness I ask myself)

The image below was taken at f13 1/160s Ive done some slight work in Photo Shop To me the image looks sharp there was obviously plenty of light but if I had taken this image at f8 would that have made it even sharper ?

The other question is when focusing with this shout should I have say used a centre focus point set the aperture to say f14 focused on the banking at the bottom right and then re-composed the shot to give max depth of field (is this roughly what hyper focal distance is)

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Chap......
http://blog.paul-hirst.com/