I don't know how good the sound is.
Generally digital camera sound is basic, and consists of AGC (automatic gain control) only.
But since you are recording yourself, you should be able to achieve the necessary adjustment by just speaking softer or louder. Most digital cameras do well with voice recording.
Recording live music is another matter, because the live music is usually too loud and it overdrives the microphone circuits.
If you want to use a separate sound source and blend it with the video, you should be able to do that easily if it is voice-over. You just need the necessary software program.
I can't help you with that.