The orange in Mediterranean areas was a bitter green fruit. When the Portuguese arrived in China in the early 1500s, they found a different, reddish, and sweet orange and brought it to Europe. So, many countries, from Greece to Pakistan, named this new orange as 'Portugal', and the fruit gave the name to the color.
Citrus plants require a very similar watering regime as any other houseplant. In the winter, allow the soil to dry out between waterings, as they do not like overwatering. However, in the summer, they need to be watered more regularly, possibly once or twice a week. Ideally water with rainwater if available.