Short answers, pulled from the story.
The first schism creating the Mahasāghika community occurred 116 years after the Buddha's nirvāna during or after the reign of Ashoka Maurya. Scholars Jan Nattier and Charles S. Prebish date this division to that specific period following the Second Buddhist Council.
The Mahāsāghikas advocated for the transcendental nature of the Buddha and taught that his material body is unlimited with infinite supernatural power and lifespan. They held that arhatship was a lesser form of enlightenment compared to the status of advanced bodhisattvas who act out of free will to liberate sentient beings.
The original center of the Mahāsāghika sects lay in Magadha with important sites including Mathura, Karli, Amarāvati, and Nāgārjunakoñdā. The Caitika branch focused on the Coastal Andhra region while other subschools existed in Gandhāra, Kośala, Eastern India around Vārānasi, and the lower Krsna Valley.
The Mahāsāghika Vinaya provides insight into the format of this school's textual canon by appearing as an older redaction with fewer stories than other versions. It differs most from other recensions in structure though the rules generally share identical meaning when Vibhangas are compared.
Paramartha wrote about a special affiliation where much of the Mahasamghika school moved north of Rajagha to discuss incorporating Mahayana teachings formally into their Tripitaka. Historians like Andre Bareau trace the origin of the Mahayana tradition to these older Mahasamghika schools in regions such as Odisha, Kosala, and Koñkana.