The Bricks node puts out a random-per-brick blend of the two input brick colors, biased at Bias = -1 to Color 1, and Bias = 1 to Color 2. So you can quantize the blend, and map it to colors, as much as you like:
I've added a tree which uses the range of colors to switch between completely different textures:
The following script allows you to create a material with the colors you'd like and assign it to a specific object. The material is only created once, if another material with the same name already exists that one is used. If it finds the expected shader node it sets the desired color. The first argument is the object you want the material assigned to, which ...
That's one use case for Node Groups.
Select all relevant nodes and group them with Ctrl+G. This way the created group is accessible within all material node trees, located in the Add menu: Shift+A > Groups > Your Group Name
Save your config as well as the created node group as part of your Startup File under File > Defaults > Save Startup File
You can try this:
Open your obj file with a text editor
Remove any reference to materials in the first lines
Remove any reference to materials in the last lines
Look for the faces definition section, a face looks like this:
f 6/4/1 3/5/3 7/6/5 ...
Three numbers for each vertex (position coord./texture coord./normal vector) –
find a way to delete the ...