When in the DMU Public "help" area, at certain angles pretty much everything becomes x-ray. Strange. It's also really hard to navigate the area while the surroundings keep turning into the void.

This is probably because you have optifine installed with "Fast Render" enabled. You can fix this by either disabling fast render or by turning off BOTI in the dalek mod config

 1. Fast Render is off by default, and I haven't touched it at all

2. I don't think BOTI/SOTI has anything to do with it, because:

a) I don't think the /warp help is a Tardis

b) This doesn't happen in single-player when in Tardis or out of Tardis

It's a BOTI related issue. In the second screenshot you can see the Gallifrey Falls painting which uses the boti effect 

If you have any shaders on or fast render (which you've said you haven't) then it will cause this to happen