You may need to Soften your edges. Edit Polygons > Normals > Harden/Soften Edges > OPtions. Choose All Soft and apply.
If that's not the case, then perhaps a screen shot or something might help?
As for the extruded surface, the main thing you want is efficient geometry... you don't want more faces than you really need and the ones that you do have, you want to be fairly neatly layed out. Also, after extruding (I'm assuming you used the Surfaces > Extrude... sometimes it can get a little confusing), your original curve still has its history, so you can adjust its CVs and it will adjust the shape of the surface.