Is this realistic or can I miss some of this detail?
Do what makes you happy.
If you are not sure then do the basic colours, and if after playing you feel you are left wanting, you can always go back and add more detail later.
Terrain depends on what theatre I guess.
The desert stuff would certainly be something you could scratchbuild.
Stalingrad not so much!
Leven Miniatures seems to be good value
