Multiplayer game sounds

I've got a server-client based game and there are few things I want to do: a)I want to have some ambient sounds and background music for everyone b)I want players to have footstep sounds that others can hear

For a) it would be best is the music was only played let's say on the server and be heard by everyone who connects OR it could be played on each players client for him or her only, so that others won't hear it. I'd like the first option though

For b) - since other players are just GameObjects that move according to the information sent by other clients, I only need to set that when the objects move on my client I hear the sounds.

Sadly multiplayer is still a little bit of black magic to me and I don't truly understand how does it work, so I'm begging for some advices. Thanks in advance!