Leopard1212 wrote:
Assume I need to re "download" my apps. Will I lose my playlists?
No, and No.
Joining Family Sharing does not remove your installed Apps or affect your playlists in any way.
Family Sharing is designed so each person uses their own Apple ID and as such your own app purchases and own playlists separate from everybody else. If you are trying to log into someone else's Apple ID, then you are doing it wrong and defeating Family Sharing entirely.
Family Sharing simply allows people with different Apple IDs to share purchases and contents. It does not impact how your device works or has worked before.