Skyboxes:
i'm still working on this one (to let you view them in preview at least)
right now you can only set them if your map is in the custom folder
and you have a script set up for it (an example on how to do it is Zortch\custom\cutmap2.script )
Mixing textures:
for posters I recommend using separate geometry and placing them near the wall
another alternative is to split the walls (quad edit mode (M) mode 5)
you can make a terrain plane by pressing T and dragging it around (works similar to box creation)
(also quad edit modes 7 8 and 9 are designed to work with this kind of geometry)
to mix terrain textures you can set textures by vertices:
- enter quad edit mode (M)
- enter mode 2
- here you can select vertices and use Q and E to set textures on them
(note: blending textures this way doesn't work on BSP )
Instadeath:
there is no insta death in the game (or at least there used to be but I don't remember leaving in anything capable of it)
there are a few alternatives - there are ways for making ground that can hurt you:
just leave a hole in the ground - if you fall of the map it teleports you to the start
you can place lava (set the texture to the red lava texture - only works on ground that you can walk on - works similar way to damage in doom)
press V and draw a zone
in mode 6 (properties)
hold E and set the zone to be Lava or Nuke
and I don't recommend it but you can make a mover that can hurt you by:
making a box
select it
in mode 6
set it to be Drill