iBroadcast lets you upload your music and listen to it anywhere - phone, browser, or offline access. I have like 42,000 songs and I've been using it for years. It's awesome.
To get the mp3s, I still use the website that's often referenced in old /mu/ memes/instructions.
I'm pretty sure it hits all your features - I'm not sure about lyrics though.
Idk if it's actually open source, but they seem to be going on the open source financial model: make an awesome thing and then survive on the generosity of people with money who appreciate it.