La Réunion is a French-speaking island, be aware that English are not spoken everywhere. People are in general nice and try to help out as good as possible. Most of the tourist on the island are french people.
The island is small and easy for self driving. They have a good infrastructure, many signs in order to find places. Traffic information can be found on digital signs by the highway – all in French.
The easiest way to get around in La Réunion is by renting a car. Direct pickup at the airport in Saint Denise possible. In general the streets are good. The island is surrounded by a highway near the ocean, as well a highway through the island. Smaller streets are tight and can be rough.
In general all the places take credit card (restaurants, entry fees, …). Have some cash (euro) with you, in case wireless connection is not working at remote places and with it the credit card machine.
The island is an outdoor paradise. Most of the hikes end at a waterfall, river or lake, which can be used for swimming and refreshing. The island provides half day, day and multi day hikes. A huge trail system allows hiking through the highland and sleep in mountain huts.
Due to the fact that La Réunion is a tropical island be prepared for sunny hot weather or/and rain. It will not be colder than 25 degrees. Beach area hold arround 30 degrees. In the highlands it is a bit lower (20 to 25 degrees). During hiking, always have water, suncreme, a sun cap and a swimming suite with you.
La Réunion is a small island, if you are planning to do a multi day hiking vacation + 1 or 2 days at the beach plan in 10 to 12 days. If you are looking for day hikes and seeing the main attractions plan in 7 days.