er… not quite. A German would understand “Where is the dumpling/the lump?”. Better to ask “Wo ist die Toilette?” (Tooahlettey). When speaking English better ask for “the toilet” as the “bathroom” euphemism isn’t widely understood. Toilet doors are variously marked “WC”, “00”, with male/female stick figures, with cutesy symbols of boys/girls peeing or “Herren”/“Männer”/“Damen”/“Frauen” (gentlemen/men/ladies/women, respectively)
Bitte (please) and Danke (thank you) will go a long way. English is spoken by most educated people, at least those aged, say, forty and below (an educated seventy year old German might have learned Latin, Greek and French instead…). Pronounciation, though, is usually either excruciatingly bad or British. Rudimentary French will be much less use than native English.
If you travel by train it might be a good idea to eschew suitcases and tote a big backpack. More practical for entering/exiting the train and for walking around the city centre without needing a taxi at once.
A railway timetable database is available at bahn.de. Long-distance trains are most crowded Friday to Sunday, of course - you might prefer to take out a seat reservation on these days, available at the Reisezentrum (ticket office) in the station, as is on request a printout of your rail itinerary for a given connection.
Cities I’d recommend to visit:
Hamburg: city with a long mercantile/maritime tradion. Good walks are the port (station Lanungsbrücken, best walk along the harbour promenade and take a one to two hour boat trip through the port, and also along the Alster lake.
One of the older, smaller North German cities such as Lübeck, Celle, Hameln (Hamelin) or Goslar. Nice historic parts of town.
Hannover: doesn’t have a touristy reputation (more known for its large pedestrinanized centre dedicated to the shopping deities) but a walk along the Maschsee is lovely. Good to live in with its large parks and city forest.
Stuttgart: big but more provincial in outlook.
Munich: overrated IMO
Towns on Lake Constance, such as Konstanz or Friedrichshafen.
When exploring a city, Bratwurst, Currywurst or Döner from a stand or hole in the wall are much preferable as fast food to McDonalds’ offerings.
If you eat in a restaurant you mostly seat yourself. In the more down-to-earth classes of restaurant, when it’s crowded it is not bad manners to ask if you may share some other party’s table, and then respecting the other party’s privacy if they don’t indicate they like to talk.
The big problem in most German restaurants is: when you have ordered and eaten, the waiter won’t present the bill unasked or otherwise indicate that you should leave. In the evening they will be perfectly content to let you linger for hours and hours after your meal (because that’s what many Germans do after their meal, with the occasional refill…). If you do want to leave in short order this might be a problem. Don’t be shy - signal the waiter energetically or even walk up to him/her.
Anyway, you will be very welcome. Please don’t misunderstand our not smiling at you - we Germans may look a morose lot sometimes but that’s not to be taken personally, it’s just that we only smile if we are really happy rather than by default.