Short answers, pulled from the story.
Alara Kalama was a hermit and meditation teacher who practiced as a śramaņa, a wandering ascetic seeking spiritual liberation. Buddhist scriptures identify him as the first teacher of Gautama Buddha before his enlightenment.
Siddhartha Gautama traveled to Vaiśālī to receive instruction directly from the hermit. At this location, Alara taught specific early meditation practices including the sphere of nothingness.
The curriculum included a jhāna state known as the sphere of nothingness which required the practitioner to transcend all perception of form and sensation. Students learned to focus on the absence of objects rather than their presence to quiet the mind completely.
Siddhartha declined an invitation to lead the community jointly because the dharma did not lead to freedom from samsara. He sought further guidance beyond what Alara could offer to end the cycle of rebirth entirely.
After attaining Enlightenment, the Buddha went to find Alara Kalama again but discovered that he had died seven days prior. The news confirmed that the opportunity to teach his former master was lost.