Apple iphone 4s

[swan2043]

New to smartphone realm

My wife wants to get a playlist and play in bedroom and also have a speaker next to the computer. Our concerns are number one how to do this (get songs from Spotify then get them into iphone then play on remote speaker) Number two is data, so we have enough with 16g ?

 I cannt seem to get a straight answer in the search feature here. Some say it 'eats up the data" others say not that not much data is used

please help

I suppose we need the apple "air player" for the speakers as well as wi fi

Glen and wife