Excellent questions @F50! The device is indeed capable of battery power or power supplied by plug outlet. This will change automatically when the plug is introduced or unplugged. When plugged in, your device should prioritize the use of power, over battery power.
As for the features available, they are the same whether using the battery only or plugged in to power. The only difference is that some features might benefit most from a plugged in power source as the frequent use of robust features on battery only, might drain the battery quicker. I hope this helps!