Treating 3d "solid" like solids

I'm new to the 3d community and coming from an conventional art background and being much older than most beginners I have had some frustration with the fact that 3d models are not treated as solid. The two examples that come to mind is 1) in edit mode I can select several vertices on a surface and if I'm not careful vertices will be selected on the "backside of the object" and then messed up when I manipulate those I can see. This happens when I am not in wireframe mode and I find it very frustrating for a beginner. 2)The second is how light often seems to "shine through" a solid object and case inconsistent highlights and shadows on the object's various surfaces. If I've totally missed some settings that would prevent these scenarios, then please enlighten me, otherwise, it seems like fixing this would help encourage new people to get involved with this otherwise wonderful tool.