Unity editor like Hammer editor?

Questions & Answers
1

Is there any way to draw geometry and add a tile texture to this like in hammer editor or unreal engine?

2

Check out SabreCSG. Its a CSG tool that lets you add and subtract brushes like in source.
You can also do all the texturing like in hammer

3

You might also be interested in Unity Asset Store - The Best Assets for Game Making
There’s an evaluation version available here RealtimeCSG