STXI sort of preempts part of the critique by making it a plot point that unlikely coincidences are happening. That is, "fate" is conspiring to bring Kirk and his crew together in this alternate timeline, in order to make it more like the "prime" timeline.
Supposedly, "fate" always was part of this Trek timeline business, as almost all the time travel stories hinge on major changes in the past taking place, and then being only partially undone, but the present that evolves from this only "partially repaired" past is still identical to the one we've learned to know and love. Time seems to repair itself somehow...
As for the specific story points of this thread, getting sucked into Vulcan should not have been a problem with "real" black holes. But it was a problem with red matter holes according to our heroes - the Enterprise
herself was said to be in such danger if she failed to leave Vulcan orbit in time. And later we saw red matter almost suck the starship in when only the insignificant mass of the Narada
was available for the black hole. So the original question is quite relevant.
And yes, I go with the crowd that says Spock was nowhere near Vulcan. After all, he was sharing a planet with Scotty who showed no signs of being anywhere near Vulcan! Plus, it was a planet with almost unbroken cloud cover. Nero could not have counted on Spock seeing anything in the sky, not with his eyes. But Nero could probably have counted on Spock witnessing the destruction of Vulcan even lightyears away: Vulcans are established as having that ability (TOS "Immunity Syndrome"), and perhaps Romulans have it as well.
As for the second point, the altitude was never made explicit or easy to estimate - but we saw it took exactly 68 seconds for Sulu to fall from the platform over Vulcan to the very surface, in a constant-dialogue, real-speed scene. Sulu (and later the Sulu-Kirk combination) would be falling at about human terminal velocity, which (assuming air resistance roughly similar to Earth atmosphere at about sea level) would give 3.6 kilometers or 2.3 miles of fall (sufficiently supporting the assumption).
So, our heroes would be breathing mountain air, with possible health consequences, but wouldn't be at Everest heights yet; the struggle could take place without extra oxygen or without our heroes or villains fainting.
And clearly it wasn't too windy there near the drill. We don't know enough about Vulcan to judge where its jetstreams might be found, but 3-4 kilometers probably isn't it yet.