Hi! Nice to have someone else interested in learning the run. The SRC forums aren't very active, they don't seem to get checked very often but there are people on the discord that are willing to answer questions (though sometimes there can be a bit of a delay). So please feel free to pop in there for any questions. Some of us are working on making notes that can be used for the run and personally I am working on making a speedrun tutorial video for the game that hopefully will be up in the next couple days.
A 100% run that includes doing all autopsies would require three playthroughs because they can only be done with Max and he can only examine the mantorok zombie then the zombie, bonethief, horror and guardian of the ancient that's been chosen as the enemy.
So we could make 100% either a '100% 1 path' where you only get the autopsies available for that path or accept the need to do three playthroughs for a "true" 100%, if the latter I would say the need to collect all the other items could be reserved for the third playthrough, since you can't carry things over between paths. (I think the former is more reasonable, because 2 extra playthroughs just to get the autopsies might be a bit much)
As for 'Chattur'gha%' or 'Ulyaoth%' those are in the same section as 'Xel'lotath%' just all under the category of any% :P
-Wyrm
I use Ulyaoth because his zombies blow each other up, so when one of his zombies has a rune can just kill a normal one rather than fight the tougher one. Also in Xel'lotath you do need to deal with a Chattur'gha Horror in Max's chapter but with Ulyaoth it's a Xel'lotath horror, which is much easier to kill. But to try to get a more concrete answer to the question, I've been gathering IL times with the various paths using the jump to game feature. Only just starting this project but I'll post the results when I've finished with it.