complicated polys

Reading up to tutorial 10 makes me wonder a little...(I probably gonna have an answer when I read further, but I am eager to know now)...in drawing all the poly''s we used the coordinate of its vertices and, this doesn''t sounds like a very good idea when u are drawing up some complicated polygones such as a face??? it seems that an irregular shaped 3-D object is rather hard to draw by specifying vertices, isn''t it??? so how is it really done in the real world...say you want to draw a landscade with some small hills? also, like the cube in the earlier tutors...can u keep somebody from "zooming" into the cube? it doesn''t make sense to me when the cube is wooden, somebody can wander right through the surface...I think we can write code that goes like when your Z is larger/smaller than something, then u can''t increment it anymore...but I find it hard to come up with a code when the box is arbitarily rotating....this is very broad I think...so just gimme some hint where I can start my own thinking.