The
Defiant will be a 180kT ship and will have access to a nice compact mount intended for use with its pulse phasers. Among ship-obsessed Trekkies, the general consensus is that the
Defiant is 120m and not 170m as indicated in DS9TM.
The
Galaxy will be larger in kT size, but will not have the special
Sovereign mount that will help the latter kick butt against the Federation's foes.
Quantum Torpedoes will be an extension of the torpedo research tree for the Federation only. The major difference between the Quantum and Photon torpedo is that one is blue and the other is red
.
The
Vor'Chas in DS9 are still actually the blue-cyan colour they are usually, it's just shown really dark so it looks greeny.