The arrows don't actually come from the item texture, but instead from the item texture copied into a portion of the arrow entity textures. So it has to be specifically designed to work with the pack. You could change the entity texture as you wish, though, as long as it doesn't break the control pixel (and you probably want the original there just in case iirc)

The pack does include tipped arrows, but since the real model doesn't differentiate between different tips we can't change it based on things like that with CEM-S (unfortunately). So, the tipped arrow looks like a normal arrow just like in Vanilla. The most customization you can do with CEM-S that I can think of is maybe based on what dimension you're in, nothing else with added dependencies (unless someone else has another revolutionary stunner).