basically, sub-d is just a method for smoothing polys (from what I've been told, not necessarily very efficient, but I don't use them much, so I don't know about that). It allows the retention of sharp edges, but not sharp corners.
I think largely its used for organic end-modeling (Gollum was made with sub-ds). Polys are terrible for trying to do curved surfaces, but NURBS have an even worse time with sharp edges. So sub-d is a compromise - you get sharp edges where you need them (mostly), and can easily do curved surfaces. I think (but I don't know for a fact) that most machine modeling is done in polys.
Anyways, the bevel and smooth stuff can be used by selecting edges or points or faces or whatever, and then hitting the appropriate buttons. In the 'Edit Mesh' section, I think it was (under maya 8). Actually, you may also want to read up on messing with normals in maya - you can get a surprising range of results just by changing how light changes from one surface to another.
That said, most objects in the real world rarely have a poly-sharp edge. So, doing partial creases on things in sub-d may actually work out (and you should be able to use fewer divisions, too). However, if you do need sharp corners, you're going to have to go poly, not sub-d.