When it is picked and used in its entirity, barley is a whole grain. Pearl barley is de-husked so it would not be considered a whole grain.
Carbohydrates, protein, etc. See related link below.
Obviously not. A malting of Wheat will give you malted wheat. A malting of Barley will give you malted barley.
No, but they are similar. Wheat has more coarser seed head than barley does. Barley is more smoother up the seed head with longer awns than wheat. Barley and wheat are two different species, though.
No, Barley and Wheat are different types of grass.