I answer for your following question here:
1. WWC
2. While making the float declaration, 1 pixel is added every time it is used in the form of the border, and even more float is allowed thereafter.
3. Aural – for sound synthesizers and speech
Print – gives a preview of the content when printed
Projection- projects the CSS on projectors.
Handheld- uses handheld devices.
Screen- computers and laptop screens.