I am arriving in Berlin on a Monday and fly out the following Monday.
For my itinerary, I plan to purchase a single trip ticket for my arrival day, and then a 7-day pass to use from Tuesday through the following Monday. I am still deciding on whether to do ABC or AB and just buy the extensions since I am not sure yet on any Zone C trips besides Potsdam (and since Wittenberg would need a different kind of train from what I can tell). I may get the ABC for peace of mind since that is 49 and the AB + round trip for Potsdam and the extension on departure day already takes it to 47.80
Anyway, my questions are:
1. Does the BVG app work offline? ie, if I wanted to pay for my pass ahead of time and have it starting the Tuesday I arrive, will the app work if data is off on my phone? I generally avoid using data when traveling and only do WiFi at the hotel as I plan my day. But if that would create an issue for being scanned and checked by the ticket checkers, I would just buy a physical ticket.
I actually prefer a physical ticket for these kinds of things, since I like souvenirs that don't take up a ton of space. This leads me to my second question.
Is it possible at BER airport to pay with a credit card to buy a single trip ticket for immediate use as well as a 7-day ticket to begin the next day? I understand I'd need to validate the single use ticket before riding into the city and, I think, validate the 7 day one the next day and then just keep it in my wallet. I ask about the credit card because I have seen some older posts on other websites indicating the BVG ticket machines only took certain cards to pay that seemed only for locals. I hope that I can pay with a visa credit card, but figured to ask ahead of time to be sure.
Can you get an area C-extension on a physical 7-day pass, or do those only work on the app? Thanks!