It depends what type of crab they are. Most have claws and are small, but there are some that are huge and bigger than an average man.
No. They look more like lobsters.
Crabs are generally transferred much like fleas from contact or close proximity, these crabs don't look like the crabs from the ocean they do not have pincers in that sense.
pea crab
They look like cherries that are blue and yellow.
King crabs have elongated legs that are out of proportion with their bodies. They come in different colors such as red or orange.
Sand crabs are small crabs that have no pincers. They are usually white or very light in color, and resemble large fleas.
poop
By its' legs.
You can get body crabs from clothing that has been worn by anybody that had body craps.
No. While all sea crabs are crustaceans, the human parasites (crab lice, genital hair "crabs") are insects, Phthirus pubis.
Yep only slightly smaller with a lighter colored shell.
Crabs have no inner skeleton like humans do so the shell is its skeleton but on the outside of its body. The shell protects the crab from injury.