[DurianHunter]

I recently swtiched from an iphone 4 to a Samsung Galaxy S6 and I have a few questions.
1. Are you able to get music app/widget permanently on your lock screen. I seem to have "my data manager" permanently on the lock screen so I'm wondering if you can do the same thing with the defualt music app/any other free music app.
2. Is there there a way to have the volume bar on the notification panel when you swipe down (like the brightness bar). Even though there's a sound vibrate and mute button, i think I would find it easier if there was a volume bar as well.
3. Can I disable cellular data for certain apps. I know you can disable background cellular data usage for apps but is there a way to completely disable internet usage for certain apps without disabling mobile data.
4. Why are my pictures sometimes darker than what they appear on the when I take a picture? Is it because of the lighting?

Thanks.