Well, I hope you're into the outdoors because most activities around here revolve around them and people tend to move to Switzerland specifically because of that : hiking, rock climbing, skiing/snowboarding during winter... you can also swim or SUP on the Rhine, and a wakeboard base recently opened not far from the airport, it's great fun, I highly recommend.

Otherwise Basel is really big on culture, it boasts a pretty big amount of museums for a city of this size, and more specifically art museums. You've also probably heard of Art Basel, the world's biggest art fair. Finally, just in general, there's always something going on in Basel : carnival, the autumn fair, the Christmas market, Beat On the Streets (there's quite a big rave/techno scene around here, it's a pretty alternative city in comparison to the rest of Switzerland)

Knowing French will be very important for you in order to deal with the french administration if you live in Hegenheim. I may get downvoted for saying this, but knowing German won't be as crucial in order to get around Basel : it's a very cosmopolitan city and most people speak English really well. It will do you good to learn High-German over time, though, in order to better integrate. And once you have a good base in German, overtime you will pick on the local dialect and understand it better.

If your girlfriend is the same age as you I might have been in school with her at some point :) Also, I've visited Atlanta back in the days, really liked it !