Kiraly utca 100 German food, truly excellent. Try sausages for lunch and grilled turkey for dinner. Terrific hash-browned potatoes. Not cheap the Pizza Hut mentioned below is at the corner of Kiraly and Erzsebet Krt. Walk up Kiraly, with your back to Pizza Hut, or take the bus.
Deserts are a special treat in Budapest.
Cafe Mozart on Erzsebet kt. New York Cafe Erzsebet Krt. You will have a guidebook, but here are some suggestions to start with. I walk wherever and whenever I can. You will appreciate Budapest much more on foot guided by your map than with a tour guide in a bus.