Multiple questions (mesh/3d view) First off, please ignore my name, it is just for fun.
Second, I would like to ask a question (two questions technically about the same idea) regarding modeling and then I would like to get help with a specific setting that I use very often and has no shortcut key.

1.) Mesh:
When we work in mesh modeling and we assign to the mesh different materials, would those material's setting for the type of preview render count toward the final view of the object (after we exit mesh)? What I mean is that influencing the outlook of the materials if I set e.g. flat or sphere? If this influence it, then what type of preview would be best to leave when we working in the mesh and give different materials to different parts that might be round/semi round, flat and so on? I know there are multiple questions in this, but I just want to understand it better because I see absolutely no change in whatever preview I choose in my final object. Perhaps my PC is not good enough to show it, I don't know.

2.) Key binding:
If someone knows how could I add a shortcut key for toggling Material View, that would be helpful. Something like Z toggles Wireframe View If there is some key that is not bound by default at my left hand zone, then that I would like to be added (doesn't matter if is with shift/alt/ctr the shortcut). I use all default settings, I have got used with that except the background colour that is a bit lighter then standard so that I can work better in wire frame.

Thank you for all the answers, sorry for my bad English.
I'm unfortunately unable to answer your first questions. Hopefully someone else can explain for you in more detail how that works.

Regarding the keybindings, I have a solution for you. If you don't use all of the standard shortcuts to change Methods to display/shade objects in 3D view, you can easily change one of those shortcuts:


Go to File > User Preferences...
Go to the Input tab
In the list, open 3D View > 3D View (Global)
Scroll down to Context Toggle Values (there should be three of them)
Open one of them that you don't use
Change the bottom Value to MATERIAL (keep the first SOLID if you want to be able to toggle between them)
Click on Save User Settings


If you use all of the shortcuts under Context Toggle Values, then continue from step 3:


Scroll all the way down to the last shortcut in 3D View (Global) and click on Add New
Open your new shortcut (named none)
In the box that says none, type wm.context_toggle_enum and press Enter. The RNA box should have changed to WM_OT_context_toggle_enum
In the Context Attributes box, type space_data.viewport_shade
In the upper Value box, type SOLID
In the lower Value box, type MATERIAL
Set the shortcut to whatever you like. I would suggest Ctrl+Shift+Alt+Z, to not interfere with undoing/redoing (press on the button that says A and check the checkboxes for Shift, Ctrl and Alt)
Click on Save User Settings


And that's it! (I've tested this with Blender version 2.76b.)