Usually there’s no ‘wait-to-be-seated’. If you enter a restaurant it depends what type it is — in most simpler places you can just go ahead and select a free table. Sometimes you are immediately greeted by a host or any other service personnel and they ask you if you come for food and/or drinks. They will then suggest a table and show you the way.
In top restaurants you will most likely be greeted by a host and he/she will lead the way to your table. For many of the top restaurants or trendy restaurants it is advised to make a reservation in order to get a table.
It is usual in Germany to stay at your table as long as you want and continue to have drinks after you finished your food. You may certainly also use the bar area if present, however, the service person will not pro-actively bring you your check — you should ask for it whenever you are ready. It is normal the your waiter will stay and wait for you to pay (either cash or Credit Card where accepted). If you pay cash it is common that you tell the waiter how much you want to pay including tip. Let’s assume you have 55 Euro to pay for food and drinks you would tell the waiter: “60 Euro”. So to speak you announce the tip. more about Tipping in Germany.