As for regenerative shielding, I am willing to give it benefit of doubt, may be it was retrofitted for "nemesis", or may be it was there, since Geordi does mention that it is the most advanced ship in the fleet.
It's definitely a possibility. The shields didn't appear to be regenerating so well when the Scimitar
was poking holes in them in Nemesis, but since I'm not entirely sure what this term is supposed to mean, that may not be relevant.
[ In many fleet battles in DS9 the Galaxy Class ships used their phasers most often.
Um, wouldn't that apply to almost all Starfleet ships in any battle?
Perhaps not in high-warp battles.
But for some reason, in the Dominion War as depicted on DS9, everyone frequently decided that they'd arrange into "lines" in three-dimensional space and wait around at sublight for the enemies to come try and "break through the lines," which they inexplicably did by also dropping to sublight, flying in tight formation with one another and moving to extremely close range with all the Dominion ships. There, many a phaser beam was indeed let loose by all those Starfleet astrophysicists and botanists and gynecologists turned lifetakers and heartbreakers.
Torpedoes should not be used at close range to the launching ship for obvious reasons, and in those confused large-scale close-in battles, detonating torpedoes would often be doing some of their work on other friendlies as well. So that explains heavy use of phasers in those situations (though perhaps not the creation of the situation in the first place...maybe huge concentrations of enemy ships have intense jamming that impede effective long-range torpedo strikes, or even "jam" subspace in such a way that warping on by them becomes an issue from certain vectors?).