OpenGL Extensions

Hey JGO,

So legacy has it that different things are supported through extensions. I have a few questions, as I need to actually implement one for the first time.

Should I have two seperate jars, one for extension based rendering and another for non-extension based rendering. The reason for this comes down to I need to support a game on a computer with OGL 2 and Shader version 1.2

Is there any difference or overhead for using extension based rendering over the bindings lwjgl has which are native to opengl?

As per the library of extensions in LWJGL, what classes am I looking to be using and are there any naming conventions I should be aware of?

Thanks in advanced! ;D