I found these three docs the other day the are relevant to what I will be doing. Seems like some of the community has set up a test suite for making sure an XS server is working with one guy having done some load testing. Unfortunately it seems the test suite and the tests done on ejabberd were done in 2008 so they might not be relevant.
I've also taken a look at XMPP. Basically (so I don't run out of time) it is a open-source server-client architecture without a main authentication server so you don't log into Google or the likes.
I checked up on ejabberd and it is in active development with the latest release last december.
More next week...