Those are not sprites, they are panels. You change the actual image by modifying the bmap property of a PANEL* object.

If you have done the lite-c workshops then you would already know this.

1) This has nothing at all to do with shaders.
2) If you knew you weren't supposed to post here, then why do it?

Don't mean to have a go but the answers to your questions are easily found in the manual and the lite-c workshops, on the 3DGS downloads page.