Grain is the biggest. Grain was to the Romans as oil is to us. The grain supply from Egypt was the most important supply line to ROme and the city even had a grain doel. Other than that in the early Rome salt was what soliders were paid in. Then your basics like gold and iron stuff like that. On could aslo consider slaves to be an important resource particularly to the upper classes.

thay supplyed medicen and sackes of grain

It pioneered architecture using columns and beams, writing, statuary, painting, and eventually became a source of Rome's grain supply which sustained the expanding city.

Yes, the poor in Rome had a fresh water supply. There were numerous fountains all over the city where water was free for the taking.

The staple food in Rome was grain. The poor could only afford to eat grain-based food. The Roman state distributed a free grain dole to the poor. Rome imported huge amounts of grain to feed her massive population. Half of this came from Egypt, the breadbasket of the empire. Tunisia, Sicily and Sardinia were the other important suppliers.