Wow - huge diorama. You have some very good ideas.
Take my comments as suggestions and pointers not as criticisms.
As Plastic Battle referenced, the wall around the outside of the diorama is a question. Is the final diorama going to be down inside a box? I would suggest considering lowering the wall if not removing it all together (at least in the final version. I understand it may help with demensions and support while under construction). Without the wall you will have an unobstructed view all the way down to street level. It will greatly enhance the viewers 'experience'.
Couple of pointers - the middle building will need to suffer from 'similar' battle damage as the two building across the street. It may not have as extensive the damage but there will need to be some. The building the Tiger is in would be filled with rubble so consider that in positioning.
Here is a link that may help with some cities
http://ardenne44.free.fr/page3.htmlBe careful of the vehicles you put together I believe the Bulldog was later if not after the war? Not 100% on that.
As far as civilian vehicles, you may have to scout out a toy store (not a Toys R Us type) and scrounge for a Corgi or some type like that. It may be closer to 1/32. But covered with rubble you won't notice the scale difference.
Keep us posted and ask more questions as you go.
You've got a good start, keep it up.