-Carving is ok only in a perfect situation, it's a part of hammer and can be a valuable tool, learn how to use it properly.
It's an obsolete tool since the Clipping tool can give the same results while keeping your map easier to mantain, and it's easier to avoid problems with the Clipping tool where they would occasionally happen during Carving.
Sure, carving
can be used, but since it usually gives a lot of problems to beginners and more experienced users know how to work with Clipping and VM, wich give much better control and possibilities...
-Inspiration is an important thing. Although it isn't technically 'mapping', one should consider mapping not only the creation of architecture and the applying of textures and lights. Mapping is where it all comes together. Story, theme, athmosphere, interaction... just a few things that are very closely related to mapping. Don't limit yourself by thinking something 'doesn't belong to mapping so it shouldn't be done'. Be creative, be open to new idea's. A recreation of de_dust, no matter the quality, just isn't interesting anymore...
-Problems? That's what test maps are for. Experimenting yourself can give some unsuspected idea's too...