Please its urgent, i'm going to buy iphone tomorrow, please tell?

Please tell there's app in free mp3 downloader in which we can download free music from free sites, please tell how many songs can be downloaded & saved in that app, and please tell can we play songs without internet connection offline in that app when we want to listen?

Itube, as many as you want, you can play without Internet but you can't get new songs without Internet