It's nice that there's now a way for The Master to appear again, though what are the chances he's now Lord President of the High Council of Time Lords by now?
No, this doesn't allow the Master to reappear again -- at least, not in the sense you're suggesting. Gallifrey was frozen
at the final moment of the Time War. This does not change any of the events of the Time War itself. It merely reveals that at the final moment, Gallifrey wasn't destroyed but was actually shunted off to a pocket universe. Everything that happened in the Time War is in Gallifrey's past at this point, so none of it was affected. So the Master would already have fled and disguised himself as Professor Yana.
Yes, I think it's a rewrite. Certainly seemed to be what Eleven considered it to be. They "remembered" doing it one way - actually using the Moment - and now they didn't, but the event looks the same in both histories, so the consequences don't "hit" until Eleven finally gets past this knot in his timeline.
But since the earlier Doctors' memories of the crossover were erased, the last memory the Doctor has is of himself standing over the Moment with his hand on the button. And then he would've come back to himself and found himself in a universe where Gallifrey and the Daleks were assumed to have mutually destroyed each other. So he would've assumed he'd pressed the button and blacked out from the effects of the Moment.
But doesn't this mean then that anything inside the time lock (which I always assumed to be a large bubble surrounding the "war zone" or maybe even another dimensional plain altogether) hasn't been destroyed, so only Daleks in orbit of Gallifrey were destroyed and not the ones left on Skaro?
I don't interpret the time lock as being anything so physically localized. It was a means of preventing those outside the war from intervening in the
events of the War, no matter where in space they were.
But who says there were any Daleks left on Skaro? There was dialogue here stating that the Daleks were throwing everything they had at Gallifrey, because this was the final battle, with both sides going all-in. All the surviving Daleks were attacking Gallifrey at once.
The Zygon storyline was naff and took up too much time. Lots of references for the continuity buffs but I really wanted 75 minutes of Time War and Doctory angst.
Ugh, no. This should be a celebration, not a funeral dirge.
Doctor Who is about fun and adventure, not endless war and death and anguish. The problem with genre fans -- and creators -- today is that we've become so obsessed with getting the genre taken seriously that we're no longer willing to just have fun. Even Superman gets a grim, depressing movie where he never really gets to be a hero.
My only gripe would've been Hurt regenerating for a proper reason and not just so the time line can correct itself.
The First Doctor regenerated spontaneously due to old age. What's wrong with the War Doctor doing the same? He even used the same line, that his body was "wearing a bit thin." After all, William Hartnell was in his fifties when he left the show -- John Hurt is 73. This is the oldest, physiologically, that the Doctor has ever been. So no, it wasn't the timeline correcting itself, because the timeline didn't change, only our perceptions of it did. This is the way it always happened. (Although there's a certain irony to the idea that the warrior incarnation was only the second one to "die" of natural causes.)
They specifically mention that the memory wipe only affects humans.
Well, humans and Zygons.
...I'm kind of glad they stuck to using only Hartnell himself for the 50th.
Not exactly, since, as I mentioned above, John Guilor recorded new dialogue for the First Doctor, dubbed over Hartnell's image ("This is the Doctor calling the War Council of Gallifrey...").
Actually, the Doctor says the timelines are, as a result of the change, out-of-sync. So when they leave, they will not remember anything about it.
It's not the result of the change, since there was no change. The same thing happened in previous multi-Doctor crossovers. For decades, fans have been asking, "In 'The Three Doctors' and 'The Five Doctors' and 'The Two Doctors,' how come the older Doctor doesn't remember these events from the earlier Doctor's perspective?" Now we know why: because when the Doctor crosses his own timestream, it throws his timeline out of sync and thus his younger selves can't remember the events after the fact.