Compounds. There are more carbon compounds than there are compounds of all other elements combined. The study of carbon compounds, both natural and synthetic, is called organic chemistry. Plastics, foods, textiles, and many other common substances contain carbon.
backplane is the shared capacity between interfaces on a switch switch fabric is also the shared capacity between interfaces on a switch and can also be the shared capacity between interfaces on multiple switches using some sort of interconnect, typically vendor specific.
Clearly forwarding rate depends on frame size. Ideally a backplane switching fabric should be non blocking for every frame size including the smallest ones (64 bytes in ethernet standard) but in reality most devices can be non blocking for an average size of 400 bytes. bandwidth: the speed of traffic.