The "standard focal length" lens (50 mm for the 24 x 36 m format) is the "standard" as it very well approximates the human eye's FOV. Generalized, a focal length of about 115 % of the image's (image sensor's) diagonal gives a good approximation of human's FOV perception.

Focussing the image is the same as for the human eye: you have to focus. "fix-focus" is not really an option.

Does this help?

The human eye's focal length is roughly equivalent to the 40-60mm range on 35mm (full-frame) sensors. That's why these lenses are called 'normal' lenses. As a rough idea, you can look through the camera's viewfinder with one eye, and directly at the scene with the other. If they look like (roughly) the same size, then the focal lengths (zoom) of the lens is behaving similarly to human vision (this trick can only be done with optical viewfinders in SLRs).

Concerning focus there are two things to consider that will be quite difficult to correct for fully. Getting the right depth-of-field requires using a sensor size that is roughly equivalent to a human retina. e.g. with an f/1.4 lens on a full-frame camera the focal depth can be incredibly shallow, and because of the large sensor out-of-focus things will be much more out-of-focus than they would appear to a human's vision. Obviously the human iris provides a continuously variable aperture, so there will be a range of depth-of-fields that have cross-over with human vision. Using a full-frame sensor would not be ideal at all though (e.g. think of a phone-camera, which will often be about f/2, but where even quite out-of-focus things have a lot of detail because the sensor is so small compared to an SLR). Something like an APS sized sensor is probably more appropriate.

Finally, there's the 'bokeh' to consider. The human iris is roughly round, while camera apertures have about 6-10 blades, which actually changes the way out-of-focus things look (particularly noticeable when photographing out-of-focus light sources like a street lamp). Many lenses do have a perfectly round aperture when set to their maximum aperture, but otherwise this is something you're unlikely to have control over.

Both the question and the two contributions don't reflect correctly the complex nature of the human field of view. The felt field of view which photography captures with 'normal' focal length objective lenses has no direct manifestation in the human eye. It is an artifact of eye movements and visal memory (located in the brain). For technical optics it is not at all a challenge to come up with an objective lens that mimics the very poor sharp field of view of the non-moving human eye. There exists a large body of knowledge about the optical characteristics of the human eye. A very readable, though probably outdated, account is Chapter 2 of the book: G. Wyszecki/W.S.Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae. 2nd edition. Wiley 1982.  

The real field of the eye, where the definition is good and there is color vision, is equivalent to the surface of the thumb's nail seen when the arm is fully extended.  That's not perceptible because the image we actually are conscious of is reconstructed by the brain from elementary patterns (Gestalts) and recognised objects.  That's why for example the moon isn't seen at its real size.