Writing HTTP-Proxy server to download music from social network

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Javascript

Java

streaming

proxy

Moved this question from Stack Overflow since guys doesn't like opinion based questions. Hope I will find the answer here.

Problem: I want to download music from social network server (hosted on another domain), which doesn't support CORS, JSONP and some other stuff to make my life more easier. So I can't make Cross Domain Request from my JavaScript client.

I need: Write a proxy server which will download music for my client. Suppose each client wants to download 20-200 compositions (400MB-4GB of music) and I must support many users simultaneously.

Questions:

1) What is better:
a) make streaming that will pass download music to the client on the fly or
b) download music to some Cloud Service and than provide a reference to the client to download?
2) Is there any ready solutions from the box?
3) What better feet my needs: Java or Node.JS? As I understand Node.JS works in single event loop/thread and isn't very good with multithreading. In other hand, do I need multithreading here even for many users?