Models don't have a surface limit; skins shouldn't either. Some player
models require more than 32 surfaces since vanilla Quake 3 did not
enforce the limit.
Skins are now limited to 256 surfaces because having no limit would
require parsing the skin file twice. The skin surfaces are dynamically
allocated so it doesn't increase memory usage when less surfaces
are used.
GL1's R_CreateImage sets GL texture to 0 before it ends, so border color is not
applied to the fog image. GL_CLAMP is not used for fog image (in either renderer),
so it would presumably not be used even if applied to the fog image.
If you tried to draw the last loaded image, gl texture 0 (which is appearently white)
was used because renderer thought the image was already bound.
Why OpenGL1 renderer binds texture 0, I have no idea. It's been removed from OpenGL2.