first of all, what is a lined barb? most barbs are schooling and require keeping more than just one for best health. same with the cory...don't get just one. I'd get a minimum of 6-8.
also, I'd leave out the rainbow cichlids. they'll get to a pretty decent size (6" for males) and I've heard from more than one source that they get a little more aggressive than most people think.