Well, they eat stuff, so...
Yes it is.
no
A cephalopod is a snail.
A cephalopod is a mollusk and an invertebrate; it has no skeleton neither external nor internal.
Yes they are
A octopus is a cephalopod that has no shell. Also squid have internal shells that are not used for protection.
Cephalopod
A cephalopod.
bilateral symmetry
The only extant cephalopod that produces an external shell is the chambered nautilus. The shells produced by squid and cuttlefish are internal.
cephalopod
Mesonychoteuthis hamiltoni
Mollusca
Scallop.