Short answers, pulled from the story.
Roman Syria was annexed in 64 BCE, when Pompey the Great had the Seleucid king Antiochus XIII Asiaticus executed and deposed his successor Philip II Philoromaeus. Pompey appointed Marcus Aemilius Scaurus as the province's first governor.
Septimius Severus divided Syria into Syria Coele (capital Antioch) and Syria Phoenice (capital Tyre) after the province backed his rival Niger for emperor. Antioch in particular had resisted Severus. The partition reduced the Syrian governor's military power, giving the northern governor two legions and the southern governor one.
Estimates for the entire Levant in the 1st century range from 3.5-4 million to 6 million people, levels not matched again until the 19th century. Antioch and Palmyra each reached peak populations of 200,000-250,000 inhabitants, while Apamea counted 117,000 free citizens around 6 AD.
Philip the Arab, formally named Marcus Iulius Philippus, was a native Syrian from Philippopolis in the province of Arabia Petraea, the modern-day city of Shahba. He became the 33rd emperor of Rome in 244 AD, during the city's millennial celebration.
In 66 AD, Jewish rebels ambushed and destroyed Legio XII Fulminata at the Battle of Beth Horon, a defeat that shocked Roman leadership. The disaster prompted Rome to send Vespasian, the future emperor, to take command of the campaign. Vespasian later used Syrian military forces to launch his successful bid for the imperial throne in 69 AD.
Roman Syria was ethnically and linguistically diverse. Rural inland areas were predominantly Aramaic-speaking, while the Phoenician coast retained a Phoenician-speaking majority into the late 2nd century. Arabs dominated Hauran, Trachonitis, and Emesa, and Greeks held the major Hellenistic urban centers such as Antioch, Apamea, and Cyrrhus. Palmyra was composed of Aramaeans, Arabs, and Amorites.