First, you are arriving at the end of the asparagus season, and if you can find a place serving it, you should partake. It is a very big deal in that part of the world. White asparagus is not what most Americans are used to, and many places will have entire menus using it in soups, salads, and various main courses. (I like mine with schnitzel.)
Second, weissewurst is a white veal sausage served boiled. It is a morning thing, usually served with potato salad and a pretzel.
Rothenberg has the Schneeboll, a pastry about the size of a baseball covered in powdered sugar (and other coatings).
My favorite snack is the cheese pretzel, which can be had with chopped ham. Check the bakeries in the morning (or the ones in the train station have them all day.)
Currywurst is actually a Berlin thing, but Bavaria had (until the late 1990's) a huge number of American military stationed in and around Munich and Nuremberg, so you find it there.
In and around Nuremberg you will find Nuremberger Bratwurst, which are smaller (about the size of your finger) and served 3-4 to a roll. Or, if you're in the right kind of restaurant, served in pairs (4, 6, 8 stuck) with potato salad or sauerkraut.
Roasted pig shoulder (Krustenschäufele) is a very regional main dish. Often served with little potato dumplings (Knodel). It is served crisp (skin on) and on the bone.
Fish is popular, and always on the menu on Fridays (you're going to be in Catholic country). Trout and carp are popular. Smoked mackerel are something you can find in the beer halls.
Chicken is usually roasted whole on a spit. You'll even see this in the snack trailers. You buy the whole, or half.
Doner is a stuffed bread with grilled meat (usually beef or chicken) and an assortment of veggies, peppers, and cheese, and a yogurt sauce. Beats any hamburger for fast food.
Pomme Frites, or pommes, are your french fries. They are everywhere. a decent place will have half a dozen various sauces. A really good place will have dozens. There are shops that only serve pommes.
You're coming just as the beer season starts. Maibock is new, the lagers and weissen beers are just coming out.
Stay away from the Hofbrau Haus in Munich, it's a tourist trap. Try Schneiders (a student hang out), the Augustiner by the Hunting and Fishing museum, or the Lowenbrau beer garden (which usually has live music.) There's a nice place on the north end of the English Gardens also.