Right on the first, Antiochus.
As for the second, the only word for "Italian" used by Virgil was the adjective Italus, which is inflected like any adjective in Latin: feminine Itala, neuter Italum; plural Itali, Italae, Itala. The form you choose will depend on your context. For example, a single (masculine) Italian would be Italus.
The adjective Italicus, which is just a transliteration of the Greek Ἰταλικός, does occur in Cicero; it would be inflected the same way as Italus.
On the other hand, if you're talking about "Italian" as a language, it would be lingua Itala or lingua Italica. In ancient times, of course, there was no single Italian language. Latin (lingua Latina) eventually came to be spoken universally, but originally it was only one of several languages spoken in Italy, like Oscan, Umbrian, Etruscan, etc.