Light already is used as a transmission source. Take a look at Fiber Optics. This is a far more controlled environment, but I'm really just trying to show the idea is certainly possible.
The problem here that you're going to run into here is the speed of light. The speed of light is 299 792 458 m / s. That might seem really fast, but distances in space are often measured in light years which is the length light has traveled after a single year. That distance, according to Google, is 9.461e+15 meters!
To put that into a little bit of perspective, the nearest star system to ours is about 4.22 light years away. That means a transmission sent from here would take 4 years to get there! Note that you're not running into a particularly slow frequency here. That is to say, using another frequency probably won't help here. You're running into the fact that the medium itself isn't moving any faster than that.
Less drastic is inside our own solar system, though even still it's not terribly real time. Take the distance of Earth from the Sun. Even though it's considerably closer than the nearest star system, it still takes sunlight 8 minutes to reach Earth. Anything further than that (like other planets, or across the galaxy) will take even longer. Still a lot better then 4 years, but not terribly great.
Another problem with you'll run into is that while space is a vacuum in terms of matter, between the numerous stars, it hardly a vacuum in terms of light pollution. Your society would need some way of reliability determining what is a transmission and what is noise from some star.
As for wormholes, it doesn't seem to help:
"If you're in a wormhole, you don't go faster than light — you're going at normal speeds, but your visualization and stellar navigation are all gone [because] … there are no stars to navigate by."
The iconic image of stars streaking by a spaceship view screen popularized by franchises like "Star Trek" and "Star Wars" simply isn't accurate, said Davis. "The light that goes through the wormhole gets distorted … you're going to have a very weird visual display."
This deals with putting a human through a wormhole, but I'd imagine the principle is the same.
Worth noting while it does mention that moving through a wormhole doesn't move you faster than light, this article does seem to think faster than light travel is possible:
At the heart of Davis' paper is the principle — supported by rigorous scientific theory — that faster-than-light travel is a real and even tangible possibility. The last section of the paper proposes nine "next steps" that would push the field toward engineering prototypes and other practical tests of faster-than-light theories.
So I'll say it's a maybe. It certainly seems plausible enough for your purposes.
A couple of things worth noting before I move to question two here is that while different light frequencies won't necessarily speed up your transmission, you could designate certain frequencies to certain channels similar to how radio waves work.
The other thing I would like to mention is what if your society discovered some other medium very similar to light, but actually moved many times faster. This would theoretically remove the distance and possible pollution problems while keeping the desirable properties of light. Just a thought.
As for question 2, I would point back to Fiber Optics. Digital communication is certainly possible in a medium such as light. Consequently, computer code and other things like that would be possible as well.