I bought a set of individual bricks and they just came in today. They come in different colors and I was wondering:

Would a wall with different colored red bricks be realistic?

If so, could I got away with NOT painting the wall? Alternatively, could some sort of transparent cover be added?

What about mortar, or lack of it?

I doubt mortar would be visible in 1/35 scale. As for painting the bricks, it is much more realistic if you do. Otherwise, it will look like the wall has been torn down and rebuilt in places. If you really want to add mortar, I would suggest Tamiya or Squadron putty. I am not sure what you mean about putting a clear cover over it. The wall shouldn't need to be sprayed with a flat clear, unless you plan on using pigments. It that is the case, yes.

Talk about a quick answer!

Thanks, I don't have to worry about mortar at that scale; I assumed not, but wanted to be sure. Also I'll find brick red paint, probably a railroad color.

You may want to use some brown, beige and orange pigments.