WebRTC vs acrionscript solutions

[SuperYegorius Zhdanov]

Hi guys! I am new to WebRTC and trying to create my first app using it. In the time when Adobe flash player was widely used I had developed my own p2p chat which could transmit video, files and messages without any server except Adobe rtmfp server. Now I want to redevelop it using WebRTC. I thought that WebRTC was gonna have similar architecture to Adobe technologies but it seems I was wrong. So I have some questions that should structure my knowledge about WebRTC in my head. I hope you will help me coz I dont know where should I start to learn this technooogy.

So here are my questions:
1. In the Adobe solutions when I wanted to connect two clients peer to peer I needed to connect to adobe rtmfp server. That server gave a peer id to each client. After that knowing client peer id I was able to set conection between each clients. Today I watched tutorial on Youtube about WebRTC and there were no any peer ids in the example.
2. Adobe has their rtmfp Cirrus server that each p2p application should connect in order to get their peer id. There was open source alternatives to that server like Cumulus server. In the tutorials that Ive seen about WebRTC js script got connected to some kind of stun google servers. What is stun server? Can I deploy it on my side? Is it really neccessary?