Short answers, pulled from the story.
Rhea Silvia was a Vestal Virgin who bore twin sons in Alba Longa. Some accounts state that Mars visited her in a sacred grove to conceive them while other versions claim Amulius raped his niece.
King Amulius cast the infants into the river Tiber but they survived with care at the site of future Rome. A she-wolf suckled the twins in a cave now known as the Lupercal before Faustulus adopted them.
The brothers disagreed about which hill to choose for building because Romulus preferred the Palatine Hill while Remus chose the Aventine Hill. When Remus insulted the new city he was killed either by Romulus or by one of his supporters named Celer.
Roman historians dated the founding of Rome around 753 BC yet the earliest known written account dates from the late third century BC. Quintus Fabius Pictor wrote history in Greek during the third century BC that became authoritative for later works.
Current scholarship offers little evidence to support any particular version of the Roman foundation myth including historical figures named Romulus or Remus. The archaeologist Andrea Carandini accepts them as real people based on an ancient wall discovered in 1988 called the Murus Romuli.