Yeah, Wing Commander - the series in general - has pretty much always been about taking the idea of WW2 pacific theater island hopping and putting it in space, with the Kilrathi essentially standing in for the imperial Japanese navy. It's hard to see in the theatrical cut of the film since so much material was cut but the Kilrathi armor is very Samurai-like and they have an idol of their war god Sivar on the bridge of their ship.
The opening was very much designed to reference Pearl Harbor, and you'll see a number of other shots in the movie that were inspired by classic ww2 movies like Tora Tora Tora among others.
I'm not sure the officer who left his post to go to the bathroom would have made any difference. It didn't delay the Confed response by much. It was a sneak attack. Also, what isn't stated in the film -though it's in the novelization and shooting script and was filmed - is that there's a different person who's a traitor on Pegasus. Somehow the traitor managed to get the Kilrathi past the Pegasus patrols so by the time the fleet showed up on radar it was too late anyway.
As far as how it affected Confed, well they lost several capships and a key naval base at Pegasus. The Concordia fleet under Tolwyn also lost several ships whose reactors melted down when they pushed hard to get to Earth on time. Aside from that, it's never stated but we can infer that there's the posilbility that other confed postions were left vulnerable by the fleet leaving to protect Earth, but nothing is explicitely stated. I'd have to re-read the movie tie in novels to say anything for certain though.