Questions about iCloud+ and family sharing, including Apple Music

I was thinking of setting up Family Sharing in iCloud+ so my sister could share my iCloud storage plan and subscriptions. I'm not clear what happens to Apple Music though, to which I also subscribe.

In some places it seems like sharing my subscription is just included. In other places it seems that sharing Apple Music costs $5 more per month. Which is it?

For AppleTV+ it's definitely not extra, right?

Also, my sister already has her own 50G iCloud plan. If she joins my 2TB plan when is it safe for her to unsubscribe from her plan?