How much power AMBEO Smart Headset drain from my iOS device?

Very little power will be taken from your iPhone when using the headset. AMBEO SMART HEADSET is designed according to the Apple MFI specification and will not draw additional power from your device or have a major impact on battery life.

ONE for iPad & Mac: What batteries are best to use for ONE ?

Apogee highly recommends using rechargeable NMiH ( Nickel -metal hydride ) batteries for 2 good reasons. 1. They last about 2 1/2 times longer than normal non-rechargeable AA batteries. 2. Rechargeable batteries are more environmentally friendly in that they are used over and over again for a long period.