True (T) - All vertebrates are chordates, but some chordates (e.g., tunicates,lancelets) are invertebrate, so not all chordates are vertebrates.
True (T) - Echinoderms usually show external fertilization and indirect development with freeswimming larval stages (e.g., bipinnaria, auricularia).
False (F) - Molluscs are not only marine (many freshwater and terrestrial forms exist, e.g., land snails); however they do have organ-system level organisation.

True (T) - Arthropods are mostly dioecious and oviparous, and fertilization is usually internal.