I am going to answer question 1a.

The Bose QC35 is vastly superior to QC15. You should upgrade only if you want better Noise Cancellation and superior sound......not for IFE but for your other devices like mobile phone music content or DAP (Digital Audio Player). Further more, you are allow to use Bluetooth wireless device on the A350 so it is also very convenient. However, if you want to listen to the IFE, you need to use the headphone cable that come with the case. I use it to listen to my A&K DAP and battery life would normally lasts me throughout a long-haul fight.

I have since upgraded to a Sennheiser PXC 550 and now, just recently, a Sony WH-1000XM2...probably , in my opinion, the best sounding noise cancellation headphone now.

(Audio)