Here it is. My fairly large collection of just about all the information that I know (that doesn't include the story line). Everything is layered so that you don't accidently read any spoilers. General information is layered in OAV order. Level one tells everything known by the end of OAV series 1, and so on.
Keep in mind, this is according to the OAV not the TV series, so if you've only seen the TV series, you might find a few inconsistencies from what you know. I will probably make a Tenchi TV version of this page later on this year depending upon free time etc.