Good corridor mission, and chopping off the third objective would probably cut the timeframe down to the ideal 45-60 minutes.
The second phase of the mission is basically
Helljumpers-Redux, but without the tanks, so you may consider doing something that spices up Objective #2.
The city-base was eerily abandoned by the time we approached it. Everyone inside was either dead or had deployed to meet us. You might toss an inside-the-buildings garrison here just to give the infantry something to do once they reach it.
You may consider some restrictive ROE on the Greyhawk - we dropped bombs in the city because it doesn't say not to, and it was a way to quickly eradicate enemy resistance so we could move on to the ridge-base in a timely-ish fashion. Without the third objective, there's less need to be as time-efficient as possible.
If there is information that has significant bearing on the mission, please include it in the briefing proper. Remember: The fluff tab does not count as part of the briefing. In this case, I'm specifically talking about IEDs being a threat - it's mentioned in the Altistan fluff tab, but nowhere in the actual Situation / Mission / Execution / Administration / Credits tabs.
I'd suggest making the objectives and win-condition clear - as a rule of thumb, I always include this info in my Administration tab, i.e.: "Mission is won if CSAT maintains a presence within <marker name = "csatwin">the red circle</marker> for five (5) minutes or if 90% of FIA are dead." "Mission is lost if <marker name = "zarosclear">Zaros</marker> is cleared of all AAF or all CSAT are dead."
~ Ferrard