Hi there,
We get this question alot, and it's probably because people go into rhino without knowing what different kinds of workflows different programes use. This is perfectly forgivable, there's enough to take in when you start out as it is.
Rhino handles meshes for conveniance more than anything else. It allows you to create meshes so that you can rapid prototype them, CNC them etc etc. But rhino is NOT a polygon modelling program. It's whole point is that it is a truly amazing nurbs modelling program, probably the best. The reason it is so good and so cheap is because it is so specialised.
If there were a polygon modelling and editing suite inbuilt then it would lose its specialism and we'd have to pay much more for it.
The thing is, you can do anything in nurbs that you can do in polys. You want to build a landscape out of contours with spot heights No problemo. It depends only on what you are actually using your model more. If it is only for rendering then it makes no difference whether the model is made using polys or nurbs, and if you have to output polys then it can make great meshes from your finished nurbs model.
Have you explored the modelling facilities at all

? You will find a method thats suits what you want to acheive, I guarentee it.
But if you really want mesh editing then rhino is not much good for you.