Mauritius is generally a safe country. Would advise to avoid walking alone on the beaches or poorly lit areas away from your Resort/ Hotel at night.
The currency used in this country is called as Mauritian Rupee
Although Mauritius has warm weather all year round, best time to visit is from May to November. December to March are the hottest months.
Tip: To avoid crowds, heat & to grab the best hotel deal July would be the best time to visit Mauritius
If you choose to stay in hotels rating 4 stars and above, then yes it is expensive. As the hotels charge the amount per day in Euros making the stay costlier.