Alright guys, you've helped me and it worked. Firstly, this is my first time on ME3 Insanity difficulty. EDI and Liara seemed to have this pact of being as useless as possible because they think it's funny. Moreover, they have some sexual fantasies of being revived by female Shepard, so they will fling themselves at turrets just to go down. So to deal with it I had to find extra safe spots for them ( cover out out of reach of turrets ) and order them to stay there. Liara behind the lowest block out of the Atlas's reach and EDI in the corner blocks with cover from two directions. Once that was done they were actually competent. But their damage seemed poor.
The guys up the ramp, for some reason, have trouble coming down the ramp. It's like they don't have permission. Anyway, it turned into a slow and drawn out battle about positioning and taking out turrets, till it was just the Atlas, thank goodness, which EDI's incineration was best for. And finally was allowed to save in the hallway.
In the second section it was just as bad, and died twice. Some sneaky engineer had ninja'd a turret at a high place just behind some rocks. After dealing with that I swear I saw both my teammates pretend to faint just so that female Shepard had to revive them, to bad everyone targetted me and it was game over. So I had to do the second section the weenie way by taking my squad back to the first area behind the wall separating the arena. I don't know how bad it would have been to tackle it the way intended, but EDI and Liara had some wimpy weapons and were better for me to pick their targets and use powers.
And so that was it. Grissom Acadamy completed. It was gruesome with the Atlas at the end, making 4 Cerebus people explode into paste before my eyes with rockets. And the combat was enjoyable, gruesome, and tense. So now I'm going to have to buy some better weapons, because my Shepard was using a Wraith 1 and Paladin 1, no third weapon so that I could get the power bonus of 96% faster power recharge. Thanks, guys!