That was sooooo cool!
10/10 I'd say!
As for whatever planet they were gating to.... um, I only assumed it was one they've already been to. Or they could have done it like they did back in 'Prisoners' - where they purposly gated to a planet where another SG team was so they could use their 'remote control' thingy for the iris. *shrugs*
One thing that got me was that Hammond asks for the 2nd gate to be taken out of storage and ready for activation - um, excuse me, but after the 'Touchstone' fiasco didn't they have a 'permenant' iris sealed over it so it *couldn't* be activated again??