What you start with is fine. If you find any Mark 2 beam arrays (of any type), you may want to replace your existing beam arrays with them. Same for your torpedo.
While the weapon and damage type matter, when you're still in your light cruiser, it really isn't that big a deal. This is a good time to just try different things you find while doing missions to see how you like them before you hit the next rank and get a new ship.