When the time lords are sending the question through the crack, how can they be? They are in a pocket universe trapped in a single moment in time (from in the 50th anniversary episode); surely if they are trapped in a single moment, that's not long enough to say "Doctor Who?" and certainly not enough to power up a truth field and project the question through all of space and time.
The mechanics of the "stasis boxes" which Gallifrey was caught in have not been clearly explained in the show. However, we know that the "single moment in time" description cannot be literally correct; it's most likely figurative. We know this because it doesn't work that way on the two other cases we see:
- The Zygons put themselves into paintings that were then taken to the Undergallery, where they somehow recognized time passing and were able to escape them.
- The Three Doctors and Clara trapped themselves in a stasis box and we see them walking through that "moment", watching events unfold, until they also escape from the painting.
Most likely, the stasis box traps some finite stretch of time in a pocket dimension, where there is no interaction with the main universe. Time doesn't "pass" in the usual sense (people don't age, buildings don't deteriorate, etc) but the people in that pocket are able to be active and move around.
In that case, the Time Lords finding the crack in the universe and sending a message through it is no different than the Zygons or The Doctors finding the exit to their paintings and walking out of them.
Time Lords can fit the large inside the small.
They are in a pocket universe trapped in a single moment in time
You've hit the nail on the head there. They might be trapped in a single moment of time, but there's a whole pocket universe inside that single moment, with a whole universe's worth of time and space. That's Time Lord technology for you: they can fit the large inside the small. In the same way a massive TARDIS spaceship can be inside a small police box, an entire universe can be inside a single moment in time.