To communicate with unknown aliens, you gotta be as general and non-idiomatic as possible. Concepts like "carbon-based lifeform" will be impossible to convey I think, unless they happen to somehow understand English (very unlikely).
I think photos are the best - even with music, it only works if they know how to play a vinyl record... and have ears!
I think since elements are a universal truth, a carbon-based life form maybe easier to communicate than you'd think. You don't need to understand English for that.
Also, yes, music and photos would surely give them the general idea about us.