Lucius Septimus mentions that he 'has to earn his salt'. In Roman times, wages were often paid out in salt ('sal' in Latin), and it is where the modern term 'salary' comes from.
Posca asks Caesar if he will accept battle, and Caesar confirms it. This was Roman custom. A commander could legitimately refuse to go to battle, and his request would be honored.
According to history, when Caesar captured Pompey's camp he found that it was already decorated for a party to celebrate Caesar's defeat.
According to history, Pompey's army had a critical weakness in that it had a large number of foreign mercenaries in it. These soldiers did not speak good Latin, and could not coordinate smoothly with the rest of the army in the heat of battle.
Most historians agree that if Pompey had held back and let Caesar's army starve, Imperial Rome would never have appeared.