1) The early Roman army was originally influenced by the Etruscans and Greeks, with soldiers resembling Greek hoplites.
2) Census reforms grouped Roman citizens into five classes based on wealth, determining their military equipment level. Poorer classes had less armor while the fifth class only had slings.
3) Marius was responsible for reforms to the Roman army, building upon earlier changes, as Rome gradually modernized its forces over a long period of time.