Indeed, tis a lot of room for the impulse engines.
I like the general arrangement, very creative. Not just a line with a bunch of smaller lines or some bubbles with a funnel. Great job on it, it's just huge for my sensabilities.
They got a lot of mileage out of those A-frame/Butress parts, didn't they?
I think a more interesting or creative possibility would to take that column structure and put it somewhere else - which several of those in the same room. The choreography of that scene would have been much cooler if that was the case. Think cooling systems or power converters? Or huge plasma injectors?
Just another avenue you could take with the poetic license of deck plans =).
Re: transporters - I rather liked FJ's setup of having several, and then having some cargo transporters and some evac transporters. Because our heroes always knew which way to go and which 'transporter room', I fankwank to say that only 1 main transporter was kept online at any given time while the other 2 or 3 were powered down, undergoing overhaul, or were being calibrated again to come online. I see it as one of those technologies that only has a certain number of 'cyles' before you have to do teardowns to see what's broken. And you'd want to limit the number of cyles each unit had - so you'd rotate - so all would be fairly ready if they had to be put to use at the same time (you wouldn't burn through 1 transporter and then go to the next, you'd want them to evenly wear like car tires).
So every duty shift knows what transporter would be designated as 'active'.