(4) Though clearly the ship was in shit shape when it emerged from the rift in 2366 and they got it fixed up enough before sending it back to 2344 to fight back, why did the crew of the Ent-D not arm it with more powerful 2366-period photon torpedoes? In fact, it stands to reason that after 20+ years of warfare with the Klingons, the phasers and torpedos of the alternate-Enterprise-D in 2366 would even be more powerful than those of the original timeline Ent-D. If the purpose of the C going back was to fight and win in order to prevent the Klingon-Federation war of the next 20+ years, after all, why would the D not do everything that it could to make sure the C won that lopsided battle against four Romulan warbirds?
Directly addressed in the episode:
"Unless we were to rearm them with modern-"
"We can't do that. If we send that ship back with new technology, we'll be altering the past."
"But that's what you're talking about anyway, isn't it - altering the past?"
"We're talking about restoring
The point was never to have the E-C win
, just to survive
long enough to be seen in the way history meant her to be seen - her crew sacrificing themselves to help a Klingon outpost.