1/ I don't recall the exact volume of the pods, but they're actually not all that large.
2. This is one of those VFX oddities I think we should put up there with a phaser coming out of the Galaxy
class torpedo launcher. Since the connecting area between the saucer and engineering hull doesn't really have a location fit for a torpedo launcher, and so far as I can tell the First Contact Nebula
is actually the physical model version (rather than the CGI one), it looks like a VFX blunder to me. (Note this is true of most of that battle scene, since there's weird scaling issues with the Sabre
class, and the Akira
fires torpedoes from where it doesn't actually have any launchers.)