^ For the Quarrian/Geth thing, I think that even if Tali is an Admiral and you saved the other Admiral before you do the reaper base, you still need to have a high enough paragon or renegade rep to get the "shout at people till they comply" options.
I'm pretty sure I did. The only thing I can think of is that I punched that Quarian Admiral who opened fire on the Geth dreadnought while I was still on it, which may have made him not listen to my orders during the climactic moment.
Either way, the Geth died. I'm okay with that.