I want to create a room, should i use 1 cube then resize or should i use 6 cubes to make a room, which way is better?
The BEST way is to create the room is by creating custom meshes. This is the way minecraft is done. Basically you create an array of vertices, create triangles from that array, and create your collision mesh based on those previous calculations.
Your room will end up being basically 6 faces.
http://alexstv.com/index.php/posts/unity-voxel-block-tutorial
This is a voxel tutorial that creates one of these meshes, which would literally be all you need!
Thank you everyone for helping me