Apple doesn't want everyone to switch to lightning. They are banking that bluetooth will eventually be the 90% even 99% standard among consumers. I tend to agree.
If you're listening via AirPods, you can't charge the AirPods
The case provides 24 hours of battery life. If you're in a situation where your case has no battery life at all and your airpods have no battery life at all, they take 15 minutes to charge.
Eh, not really. Try listening to music while you charge today and watch how slow it is to charge.
Depends if you're using a really low output USB port, perhaps?