[NwN/NwN2 style updater, please!]

I've been fiddling with Stalker mods lately, some of them, only works on a particular version of the game. You can't go back to a previous patch on Steam can you, or keep two versions of the same game? Sincere question.

[How can they solve the massive texture problems?]

Those are procedual textures, they are smaller in size since they are defined by mathematical functions, rather than pixels. Procedual textures are usefull in a realtime 3d-engine, or might be the prefered workflow for an artist working in a 3d-software (for example since they are animateable). But once the artist renders the scene, the size of the resulting bitmap will not differ.