The explosion at funnel No. 2 is only a theory. There was a list to port when the aft port boats and No. 15 on the starboard side were lowered. The "V" break theory was not only wrong it has been also debunked as wrong especially with the large tower debris from the break area.
The staircase did not left the ship out of the dome. I don't know why people take what happened at the movie set for real. It was not build as the original, also the water inside would be up under the dome and like in the movie. The wreckage also shows that it left the ship in pieces though the break aft.
As the break was at boiler room No. 1 how did that flood the main engine room sacking it down in the middle?
I don't think all five flights of stairs were ripped out or intact. I'd be surprised if this was the case. Perhaps the first two decks broke free. This could explain why there are still a few remains at the bottom. I couldn't think of any other explination as to why 8+ people said that the bow rose back out the water, which is impossible. I believe something did float to the surface, but certainly not the ship.
Also, if a sinking ship is listing to port, why wouldn't the second funnel fall in the same direction as the first? I think something would have had to kick the funnel in the opposite direction, like a dust explosion.
I could still be wrong, though, and they're only just theories like you said.