Just to point on one or two things:
According to the tech room descriptions, the Orion has been around for a while - at the last 7 years of the war.
An Orion is a big investment and takes long to build, so I wager they allready have developed weapons to use on the Orion before that.
Starting with weaker, less known weapon is o.k. - after all, technology develops during a war, but don't overo it. You don't go building 2km warships with slinghots on them..
Since a war has lasted for so long, it must have pretty depelted both sides. It is common practice to re-fit civilian vessels to act as escort carriers/cruisers. Sometimes unfinished civilian hulls on the scafflods have been used to make cariers and warships.
I'm kinda of a military freak and I've read all there is to read on the greates naval battles in history (the battles on the Pacific in particular).
B.t.w. - I say again. Do you need help with your project?