The best way to get around in the area is obviously by car. In the spring and summer, biking is also highly recommended. There are a lot of bike lanes and special bike roads with no cars.
There is a shopping mall called Kuhn.
There is a small McDonalds restaurant.
If you love the American style of eating, you can try to enjoy the Frankie's Diner. There some finger-food and also burgers are served.
In Bad Mergentheim you will find not too many possibilities to get drunken. But you will have the chance at Frankies´s diner or at the Klotzbücher restaurant (to eat there something is not really advisable).
Starlight Coffee at Kirchstraße is nice for some hot java.
If you don´t need much comfort you may choose the "hotel" Milchbar - it is very simple but they have the best and biggest pizza in the city.
Outside of Bad Mergentheim you will find a nice village called Markelsheim with many nice restaurant with a pretty good drink voucher: Weinstube Schurk, Weinstube Lochner.
In Markelsheim at each corner and in each street you will find many wine bars. In summer in Markelsheim there are at every weekend any other parties, esp. wine parties. Don´t miss them!