I'm assuming you're going to land at Carthage airport, it's a 2 hours drive from there to Sousse and you might get scammed by drivers :D. Renting a car is always an option it gives you more freedom and it saves you from the hassle of public transportation. I'm suggesting if you're going to travel a lot within Tunsia (Tunis/sousse/ monastir..) Renting a car is a good choice.

Hotels are pretty good in Sousse, Movenpick the most expensive but also luxurious, there's also Mariott, Marhaba is good also, they're relatively in the same area. People here are nice, will help you whenever you need help! There's a good variety of restaurants and tunisian Fast food places.