I always plugged it into the USB cable via the cigarette lighter. I read something on the internet about at least 10 hours of battery life.

Yes, I always have my device plugged in, so it switches on automatically and connects directly to the smartphone.
I have not tested the battery life.

Yes, this device can be charged using a USB cable. I haven't checked its battery life, which of course depends on how long you use it, but it lasts a relatively long time.