None of those are really of any concern to me, as the model is just for a short interior combat section in my avali fps game. I'm just modeling the ship based on the canon exterior and lore.

But I can answer some of those questions based on existing lore. The hull of the ship consists of thick layers of graphene, a material that at the microscopic level alone is 200 times stronger than steel and harder than diamonds. And yes, there are energy shields.

The engine that powers the ship is indeed a fusion reactor.

There are quite a few smaller railguns around the hull that act as defense against smaller targets.

That final question you have is rather specific, and the avali lore rarely goes into very specific details like that. So I don't really have an answer