Other silly things they do with music downloads:

Require amazon software to download a whole album bot not single tracks.

Gift balances aren't valid for downloadable purchases.

A lot of people are saying to go with the eneloop batteries. They do have excellent idle life, but only 2000 mAh capacity.
If you don't mind charging more regularly then the higher capacity cells might be the ticket. Then again nothing to stop you from getting a quality charger with a handful of each.