(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.
But at the same time, Ent-C had to deal the Romulans a crippling enough blow that the Klingon outpost survived in order to communicate the fact that the ship fought 4 Warbirds on behalf of the Klingon Empire to create the detente and later the alliance that the Federation and Klingons enjoyed in Next Gen time. Otherwise, what good would it have done if Ent-C returned, was quickly obliterated, and then the Romulans wiped out the Narendra outpost and the news of the Federation sacrifice died with them?
The only way I could see this working out (Ent-C survivors plus Romulan survivors with the upper hand plus Klingon survivors on Narendra 3 to spread the gospel) is if Ent-C destroyed three Warbirds and severely damaged the fourth (or at least its weapons systems) before the C was destroyed or rendered uninhabitable, whereupon the surviving Warbird retreated to Romulan space without further menacing the Klingons.
In regards to "restoring the past" versus "altering the past", well, Yar going back with the C "alters" rather than "restores", so I had rather envisioned that someone on the D may have slipped a few 2366 photon torpedoes to their counterpart on the C, just to make sure the C won. After all, it was 4-on-1 and Enterprise-C was already badly damaged from the initial volley, putting them behind the eight-ball. As one of the resident experts in such matters, Christopher
may wish to chime in regarding whether the presence of Yar on the C is an "alter" or a "restore"?