We also went through the issue with changed strats - we stuck with having just 1 mage get corrupted - she was able to handle it extremely well, and we had two spirit links to get her health up after the shadows orders. The main thing was that we had a quite definite series of cooldowns we were using on her to keep her up during each spread shadows order - eg hand of sacrifice, pain suppression etc. Kept a bubble on her at all times too - having two disc priests helped a lot with the whole raid.

We also found that persisting quite rigorously with the strat we chose for practice, practice, practice definitely paid off.

In terms of the adds being tanked, we had quite a few issues figuring out a position that worked, but ended up sticking with the stairs, and having Cho tanked slowly from the bit of the trapdoor nearest the stairs back towards the throne. As Vandreigan mentions, we had the tank move back behind us a bit, then hunters on each side MD the adds towards her - she dragged em back to where they eventually die.