For (a), this is going to be true, as the smaller ships can be built assembly line style, using mass production to drive down their costs per ton.Destructionator XIII wrote: Talking about practicality is much easier. Realistically, among reasonable sizes, bigger spacecraft are superior in every way but two:
a) They probably cost more, and thus you will be unable to operate as many of them. Storywise, this is probably a good thing, since it gives an excuse for our heroes to be the only ships in the quadrent.
b) They are limited to less acceleration, which is usually pretty irrelevant (space is so huge you can take your time), but in certain specific settings it might matter.
For (b), why would this be true? If both ships have devoted 10% of their mass to engines, then wouldn't both of them get the same thrust? I'll agree that the larger ship will have more of its mass fraction dedicated to structural mass, but the smaller ship will have to devote more of its mass to armor.
For the larger is slower, we do have the Honorverse where higher mass ships have lower accelerations, but we also have Star Trek where larger ships seem to go faster (possibly due to cross section vs volume?).