Ultravox 2.1 Usage?

[Sockets]

I'm really not understanding how the message protocol works. I feel like the wiki isn't too friendly. I'm trying to write a simple source client in C#, and I'm getting hung up in a couple of places.

1. What is the full message I send to begin a connection, and instigate a reply?
2. Is there any C# XTEA library out there?
3. Why XTEA? Isn't it weak encryption? And why encrypt, in the first place? No real sensitive data is sent.

I'd appreciate any answers!