I am Hoffenheim-Supporter and I live in Sinsheim. I recommend you for the pregame-beer the city of Sinsheim. They will have a small 'fan mile' withI think that most will be in Sinsheim before the game.
beer, sausages, music and a lot of friendly and peacefully Hoffenheim-Fans. When you come by train, don't leave the train at the station 'HOFFENHEIM', because there is nothing. Leave the train at the station 'SINSHEIM HBF' and you have not much more than a 200-yards-walk. From the 'fan mile' you have an easy 15-minutes-walk to the stadium. For your beer of disappointment after the match you should prefer Heidelberg, because Sinsheim has not really much bars. I wish you a nice journey and good luck in all other matches. Our problem is, that Pep knows our team and all around and therefore he will never underestimate us.