It's really great to hear this from you, Slin.

About input, I think it's okay as they are now: using ambient_blue, specular_blue, ... and in models use the first skin as diffuse, its alpha as specular map, second skin as normal map and its alpha as height map.

About what shaders should be there, I would say:

Object Shaders:
Normal Mapping (supporting specular)
Environment Mapping (supporting also lighting and maybe a variant using realtime reflections)
Normal map Multitexture Terrain Shader
Environment Water Shader
Realtime reflections Water Shader
Vegetation Shader
Toon Shader
Glass Shader

PP Shaders:
HDR
Shadowmapping (Sun and maybe point/spotlights?)
DOF
SSAO
Blur
Radial Blur