We consider a lower weight better because lighter devices are more comfortable to carry. A lower weight is also an advantage for home appliances, as it makes transportation easier, and for many other types of products.
A shorter minimum focal length allows you to get more of the scene in the photo, and offers a wider angle of view than longer focal lengths.
A longer maximum focal length allows you to focus in on a small part of a scene, and offers a narrower angle of view than shorter focal lengths.
A prime lens has a fixed focal length. In general, these are sharper, with a wider aperture.
A normal lens is one that doesn't fall into another category such as wide angle or telephoto, and typically has a focal length between 35mm and 70mm. These lenses aren't tailored towards a specific type of photography, and so are quite versatile.