Short answers, pulled from the story.
Śrāvakayāna translates literally as the vehicle of listeners. It names the path followed by disciples who achieve liberation by hearing the teachings of a Samyaksaṃbuddha, a fully self-awakened Buddha. The goal of the Śrāvakayāna path is becoming an Arhat.
Scholar Isabelle Onians argues that Hīnayāna is overrepresented in secondary literature, "far out of proportion to occurrences in the Indian texts." She describes Śrāvakayāna as the "more politically correct and much more usual" term employed by Mahāyānist writers. Hīnayāna was used specifically when writers meant to encompass both Śrāvakayāna and Pratyekabuddhayāna together in contrast to the Mahāyāna.
In the 4th-century Abhidharmasamuccaya, Asaṅga described Śrāvaka followers as having "weak faculties." They follow the Śrāvaka Dharma, rely on the Śrāvaka Piṭaka, and direct their practice toward their own liberation through cultivating detachment.
Gampopa, who lived from 1074 to 1153 CE, described those on the lower paths as practitioners who fear samsara and long for nirvana but mistake meditative absorption for nirvana itself, like someone who believes a resting island is their final destination. He presented the Śrāvakabuddha and Pratyekabuddha paths as deliberate provisions for "rest and recuperation." After that rest, the Buddha encourages these practitioners to cultivate bodhicitta and take up the Bodhisattva path.
A Sāvakabuddha is an enlightened disciple of a Buddha who achieves awakening by hearing the dhamma. The term is built on sāvaka, meaning one who hears. Even lay persons who take special vows carry the title sāvaka.
A Sāvakabuddha depends on a tradition that stretches back to a sammasambuddha, the fully self-awakened Buddha who established the dhamma. Without that inherited lineage, a Sāvakabuddha cannot reconstitute the teaching from scratch. Only a sammasambuddha can open the path in a world where the dhamma has been lost.