Your questions are perfect!! Probably you should ask them under FOOD DRINK etc, but don't worry, MadridMan will do it for ya! He 'cleans up' every night. For churros y chocolate, there are two times: breakfast (8-11, mas o menos) or merienda/snack (4-6+). If you are in central Madrid I recommend HONTANARES, right at Metro Sevilla (it's a tiny street, and Hontanares has a cool electronic "ticker" sign on the outside. You just saddle up to the bar, or sit at tables, and say, churros y chocolate para doce! Or whatever # of students. For tapas, there are two main areas. One are the streets in the Huerta district around the Plaza de Santa Ana. The other is the Arco de Cuchilleros off the Plaza Mayor. When I have taken groups to one of those Mesones (meson del chaminon, meson de la tortilla etc), i walk in WITHOUT the students and NEGOTIATE the price. Otherwise they do tend to, um, throw on a tourist tax! Queremos doce refrescos, pinchos de tortilla, champinion, y queso. Cuanto nos cobraria? Read next post