A: I believe you need to have a MagSafe compatible case if you want to be guarenteed to charge through the case. I'm guessing some of the other cases will work if they are thin enough.
A: Hi, terrie! Regarding your question about the Apple MagSafe Duo Charger: If you don't already have a power adapter would be needed, though it does include the cable to connect to said adapter. If you have any further questions, please don't hesitate to contact MyTGTtech at 877-698-4883 every day, between 7am-11pm CST.