a couple questions about rocket.chat

1. I have a website that has its own user login and register system (not integrated with facebook or google+ or anything else). I am hosting rchat on digital ocean ubuntu 14.04. website and rchat has different URL. I embedded rchat with frame into my website. I want to make rchat user system to be the same as the website, so when user login to the website, they don’t need to login rchat again and will automatically go to the chat room. I found whole bunch of authentication tools on Rchat docs and don’t which one to use. Which one will be the best for me to use? Oauth looks fine, but where can i find id and secret that is needed for authentication? Currenly my website still is hosted on my local machine, do i need to get the website up to online in order to do the authentication?

2. I tried to get the screensharing to work for Rchat, couldn’t work. It is using Jitsi’s service. Do i need to install something else to the server? message says it needs some desktop extension. Also i accidentally deleted the Chrome extension id in Rchat, i assume i need that for screen sharing, but how can i find back the Chrome Extension ID?

3. I read somewhere saying Rchat’s video chatting will have limitation when users are geographically diversified. is this true? what is the limitation if so?

Long questions, sorry and thanks.