Few question about watch+iPhone communication

Hi I wanted to buy new Apple Watch SE (cellular) for myself and I wonder:

1. Can use it to change songs I play on my iPhone with Apple Music?
2. Can I receive calls on my watch so that the sound is immediately (without any extra steps) transmitted to the headphones connected to my phone via a cable with dongle and the watch uses its microphone?
3. Does the iCloud sync work when watch have same phone number but different esim? I mean all the features like between my iPhone and my Mac.

I would appreciate some help with all of that :)