In our battery life test we ran a 30 minute video clip from Netflix (through Chrome) with the display at full brightness and Wi-Fi switched on. We recorded the decrease in battery capacity over the 30 minutes (9% decrease) and then calculated the time it would take to completely discharge the battery from this.
This test is fairly intensive so five and a half hours is a perfectly respectable score. We imagine that you would be able to get even longer out of it with the screen dimmed slightly and WiFi turned off.
There IS a micro-SD slot, just above the micro-USB connector. And as I have this tablet, I can confirm that it works well with 64g micro sdxc card without issues.