Gonna switch to a Note 4 but need some questions answered

[Trees]

On Note 3 with 4.4.2 and TouchWiz, the native Samsung Music player has lock screen and Notification menu controls, headphone state awareness, and some decent widgets. I've actually stayed with that as it works well and meets my needs. In the past on older Samsung rooted devices, I typically froze the default Music app and went with Rocket Player +, or PowerAmp.