If you aim for advanced stuff, then use the GLSL custom shaders. There are as of late GLScene some fixed ones translated, so you should be able to get their GLSL code and combine it. GLSL isn't all that difficult (2 days of proper study and you should be able to do some stuff in it) and it provides a truly flexible solution.

So I'd advise for you to remove all the fixed-pipeline shaders, and make a custom GLSL shader code. This way you will do the texturing + bump + normal + other mapping yourself and you can also do easy switching and other nifty stuff. It's a bit jump at start but once you get it up and running it's almost fun.

Just make sure your card has at least 1.5GL support