The device is protected with extra seals to prevent failures caused by dust, raindrops, and water splashes.
A higher screen resolution provides a sharper image, making it easier to review your photos.
An electronic viewfinder (EVF) with a higher resolution provides a sharper image, producing a view comparable in quality with the one displayed on an optical viewfinder.
The focus motor moves the lens in order to autofocus. For system cameras, having a focus motor in the camera's body allows you to use a wide range of lenses, including lenses which do not have their own focus motor. For compact cameras, a focus motor is usually built-in.
Flip-out screens can be useful for tricky shots.
An optical viewfinder (or OVF) allows the photographer to compose a shot while seeing exactly what the lens will capture. OVFs have no time lag and require no power - as opposed to electronic viewfinders, which can drain battery life. OVFs are also better in low light situations.
An electronic viewfinder (or EVF) is a small display which shows the framed image. Benefits of these over optical viewfinders include: they show more of the image; they can be more compact; it's easier to focus with digital zoom; and they sometimes offer extra info on the display (such as a live histogram).
With 100% coverage, you can compose the image correctly when you capture the photo. With less than full coverage, you may have to crop your photos afterward to get them looking perfect.
The bigger the screen size is, the better the user experience.