I've worked with Glut or maybe something similar called Glu that does all kinds of D3DX like stuff, drawing quadrics and primitives for example. This is nitpicking. An extension framework can implement whatever kinds of extensions that seem to be necessary or desirable.
No it isn't. GLUT is a toolkit for creating and managing OpenGL windows, with a few ancillary functions for doing useful things. And though D3DX provides many features, conspicuously absent from that feature list is a simple way to create and manage a D3D window. Similarly, D3DX's primary features are math functions, image loading, meshes loading, and shader/effects loading and management, none of which you will find in GLUT.