Shopping for beverages is very different in Germany than in the U.S. Many shoppers buy their drinks at the Getränkemarkt (beverage stores) around town. You can find individual beverage stores around town or within the larger grocery stores. These shops carry all kinds of sodas, juices, water and beer. Most juices are reconstituted from concentrate but be sure to read the label; there are also some excellent quality 100% juices. Lidl is a great source of a variety of juices at very reasonable prices. They also have unbeatable prices for wine and Champagne! Real and MiniMal have signs by the wine telling whether it's sweet or dry, which is great for wine novices. Something called Nektar may sound good but that means it has less than 50% real juice in it and a significant amount of sugar. Real and sometimes other stores (check Kaufland, for instance) now sell liters of Tropicana real orange juice but you'll pay a pretty penny for it. You can buy your drinks individually or in cases.
Glass bottles for beer, juice, water, or milk are returned in their crates back to the grocery or beverage store. This is also true of many plastic bottles used for cokes or mineral water. There are deposits (Pfand) for most beverage containers and plastic crates. (Bottles that say Einwegflasche or Grünerpunkt with a picture of a green circle with arrows have no refund; you have to include them with your recyclables.) Each store has its own process for receiving bottles for the deposit. In some stores (e.g., the Getränkemarkt) the cashier will either reduce the price of your new purchase by the amount of your bottle deposit or they will give you the cash back. Other stores have an automatic refund machine which gives you a ticket (Bon) which you then redeem at the Kasse.
Geith in Burghausen has an excellent selection of good quality wines, and very knowledgeable staff if you're looking for advice. They also have some hard liquors. You may be surprised to see the prices of wine in the supermarket: the California wine growers actually are really good at inflating American wine prices, so European wines which are actually really good can be had for a real bargain (by American standards). Don't be afraid to try a bottle of 2.99 Riesling!!