[X] 75-Meter Hull (+Shuttlebay)
Transporters are an obvious option - in the previous ship project, biological rated transporters were an entire separate room, and even if those aren't separated out this go around there's also the option of going for larger cargo transporters to simplify loading and unloading cargo from planetary surfaces.We are going to want a shuttle bay, we are going to want cargo space, we are going to want a dedicated workshop. Is there a third thing that we actually need? If no then I inclined to save on mass and industry in favor of being able to afford more gun.
[X] 75-Meter Hull (+Shuttlebay)
[X] 75-Meter Hull, 4 Decks (+Shuttlebay, +Auxiliary Slot)
I agree with the mathematics for this. As for future options, one question I want to ask @Sayle would be if it would be possible to design the ship "for but not with" extra impulse engines and similar - ie., if we planned for the ship to reach final production with 3 engines as designed, would it be possible to leave space for a 4th if Starfleet felt the extra expense was justified? Or would that require so much extra work as to effectively be just as expensive as installing the fourth impulse engine from the shipyard? I recall you mentioning that the ship could be up-gunned during a refit, if war seemed imminent but was not ongoing, but nothing about secondary systems like impulse engines being altered.
Also, in terms of phaser firing arcs, how wide is the arc covered by a single phaser bank? ie., would phasers spaced port and starboard on a saucer be able to fire forwards, or is their firing arc closer to 45 degrees (or less)?