II. The Imperial I-class Star Destroyer mounts Six Quad Heavy Turbolaser Battery, Two Quad Heavy Turbolaser Battery Deck Guns, and most likely Two Lateral Quad Laser Batteries, along with three Axial Defense Turrets, as per ICS and the Star Wars Technical Commentaries, both of which are considered canon. EGVV also accepts this, noting them in its technical schematic. (SWTC, EGVV pg 81-82, ICS)
III. After the loss of the Imperial I-class Star Destroyer Kotiate all Imperial-class line destroyers went through the lengthy and expensive process of 'internalizing' their Deflector Shield Generators, replacing the domes with sensor projectors to continue to fool Rebel Pilots. It is a common misnomer that the domes are indeed shield generators, as the detonation of one on the Executor-class Super Star Destroyer (Star Dreadnought) Executor, was accompanied by a declaration that the bridge shields had been dropped. Were this true, that would indicate that the [Executor]'s entire shield grid for the vessel was controlled by a single exposed dome on top of the command spire; with the bridge's shields projected by a second independant generator directly next to it. Obviously, this is physically misleading since the two generators could then be considered to be overlapping protection over each other; and since the domes are the same size of those on an Imperial Star Destroyer, it would therefore be logical that the shield strengths of the Executor-class Super Star Destroyer and Imperial Star Destroyer line would be identical; which of course is impossible. It is of a reasonable assumption that the domes on the Executor-class Super Star Destroyer were designed in the same style as those on the Imperial-class to fool Rebel gunners into targeting them; and that the loss of one in RoTJ was indictive of enough damage being done to the shielding to allow the warheads from the bombing Rebel starfighters to breach them; damaging and destroying what the dome represents (likely a sensor node/projection aparatus). Potential references may be found on the Galactic Empire Databank reference entry to the Imperial Star Destroyer line, and are too numerous to list here.