New to the Free Version

Hello all,
I am new to Sketchup. Played with Minecraft and some CAD systems. Looking for something to design a city. Have fun with a layout and buildings and roads and stadiums, etc.
Will the free version allow the design of a city or is it size limited?
Does Sketchup import DWG or DXF files? I might be able to create a layout for my city in Autocad. Or just do it all in Sketchup.
Will I be able to import 3D Warehouse items in the free version?

If you make your model efficiently and avoid excess geometry yu can model a city. You’ll likely be limited to some degree by internet speeds with larger moels so you’ll want to learn to keep your models streamlined.

SketchUp Pro and SketchUp Go do but not SketchUp Free.

Yes. You can use objects from the 3D Warehouse. Just be careful to select objects with low poly counts or you’ll wind up with bloated models that will be difficult to work with.

I presume this is a hobby thing for you. If so I think you’ll find SketchUp Free can be fun to use.