So jealous. Lived in Germany as a kid (CFB Lahr) and just spent a week there in July, including 3 days in Berlin. If I can land a job that will transfer me there for a few years, I’d jump on it in a heartbeat. Heck, anywhere in Europe, as long as I can always go visit Germany! 
Don’t you miss Berlin im Schnee and a christmas market with Glühwein (I think this word is known in English speaking coutries too) and someone singing Stille Nacht (Silent Night)?
Hey! You! Get off of my cloud! This my thread! You’re being the typcial American hijacking my thread with the nerve to be simultaneoulsy snarky! 
Jinx,
a) It is against German law for shops to be open on Sunday’s. Except for one Sunday a month; I am not sure how it is determined. Gas Stations are open however.
b1) Bags are not provided. Although you can purchase a reusable bag at most grocery stores.
b2) Normally, yes this is the case for smaller shops if you would like more of a selection find a Globus
c) Yes very much so. Still water is not the first choice so if you want it ask for ‘no gas’ and if you want free water ask specifically for tap water.
Any other nuggets of knowledge I should know along these lines: When you are ready to pay at a restaurant say Zahlen bitte
Hope this helps
Thief
Since you hijacked your own thread, let me continue by saying :rolleyes:
I fear, I have done some hijacking too. So, to compensate for that, I’d like to add some tips:
Don’t hesitate to ask people (particularly younger ones who have learnt some English at school and - in general - people sitting in cafés) for help when you are lost or want to go someplace or want to know what’s worth seeing – more often than not you will find someone helpful – and the easier it is to identify you as a tourist, the better ;).
Speaking of cafés, when you are close to a traditional one, get in or, preferably, sit outside in the sun and enjoy a coffee and some local pastry/cake/pie-specialty. Where I live, friendly looking tourists find themselves quite often drawn into conversations with people at tables close by; actually, our children have triggered more than one delightful afternoon we spent with Australians, Canadians, Americans or Asians.
And when you happen to be in a town on Saturday, you might find a weekly market somewhere in the centre (of the town or the borough) before noon: then let your nose guide you to a good baker and enjoy real bread. Yeah, we Germans are a bit funny about that foodstuff and it’s usually the one thing we miss the most while abroad – but with a little luck, you might find out why (just don’t go to a bakery chain, their products are cheap but not that good).
Once your stomach is satisfied, go out in a park – chances are, one is not too far away from you, even when you are in a city like Düsseldorf, Hamburg, Berlin or München/Munich. Of course, the weather is currently terrible, so if you are not from the north, this might not sound like a good idea – but generally it is one, especially when you are in a town with many students; then parks are usually a lot of fun.
If you find the time and are interested, go to a theatre, a cabaret or a floor show that plays/entertains you with something German. My wife is madly in love with Tucholsky, so we rarely fail to go when a female singer, a piano-player and his poems and songs work in unison to bewitch us once again. Often, when we have been at a place that featured Tucholsky, Kästner, Brecht or Robert Gernhardt or tidbits from them and other witty writers, we have had a lot of fun with the audience as well.
Whatever you are interested in, magazines with a calendar of current events are to be found in many cafés – and, once again, don’t hesitate to ask if you don’t see one lying around.
If you don’t find anything to see, you’re either in the open countryside among cows (well … I … won’t … judge) or too shy to ask.
Missed the edit-window …
Seriously, listen to something entertaining in German while you are here - the first time I was in Madrid, my Spanish amused or puzzled everyone but I still went to a play and was awed and confused and more determined than ever to learn the language.