Thank you very much for your questions! I've broken them up into headings below to make them easier to read.
1. PUEDES vs. PUEDE
You're right: the tú form puedes would most commonly be used among friends and family, while in the conversation the speakers are strangers who are politely using usted. So the answer should indeed be puede, to fit the context.
Our apologies for the confusion this has caused! I will pass this on to our audio team to see about getting this fixed.
2. SACAR vs. TOMAR
One of the tricky things about Spanish is how many different regional variations there are! Both sacar una foto and tomar una foto are valid translations for "to take a picture" in Spanish, but it is possible that one or the other won't be used in particular countries or regions. (In fact, in Spain, hacer una foto is also possible, but you're not likely to hear that in Latin America.)
The best strategy is to listen to the people in the region you visit and to follow the terminology that they tend to use. Sacar una foto shouldn't cause problems with understanding in most Spanish-speaking countries (it is commonly used in Spain, Chile, and Argentina, for instance), but if you find people giving you odd looks, you can certainly use tomar una foto instead.
I hope that this is helpful! Do let me know if anything is still unclear.