Hey Sareesh,
On your page one you mention this:
...and a 12V AC adapter (BMD haven’t said whether its 120V, 220V or both).
It's both. Same adapter for all countries, it will take 100-240V. Same as ships with some of our other products. It's a wall wart with multiple caps for the different regions.
Inside the camera, in true Apple style, is an integrated lithium-ion polymer rechargeable battery that will give 90 minutes of life (BMD has not specified whether this is standby time or recording time). It takes 2 hours to charge, so unless you are only shooting for an hour everyday, you’ll need additional batteries. Imagine what will happen if your battery dies out a few years from now – how will that affect the resale value of your camera?
Two parts to this.
Should be 90 minutes of record time. So yeah you can use an externally attached power supply to supplement this.
If your battery dies out, years from now, we'll happily replace the battery for a small charge.
Hope that helps.