it isnt a must to convert to polys some people do all there work in nurbs, but its much more difficult i know u think your model looks great in nurbs at the moment and by changing it it looks alot more awful but i would suggest to keep going as the tutorial is there to show all the work flows, most people go from nurbs to get the main shape ,then to polys to add more important detail and make sure everything is connected then finally to sub'd's for the fine tweaks. (no one said this would be easy)
the guy stuck with the neck connected to the layer go to layer right click on it then Remove selected objects then just re connect just the reference pic.