#1: I can’t comment much on this except to say I sometimes do the same thing myself. Android BLE is just kind of flaky, and I’m afraid it’s flaky on layers below the application layer. The good news is that it’s been improving with every new Android version. 4.4 was a mess…
On the other items: I agree with Duane on all counts. And I’ve run a Mooshimeter on 1.8V lithium AA batteries without a problem before.