Do not kill anything. Dont even bother. Well yea you can attack objects and stuff but don'd harm the enemies. Remember badguys are people too.

Just run for it, just jump over them and advoid damage. Try to break some health packs if you can, but make it real quick.

Yea, just kill him/her, do it fast too, dont worry about wasting your revives, you will get more after the mission.

Well evern though you didnt kill anything, might got a high school anyway because how fast you did it made of up for it. Do this a couple of time to get the materials you want, have a nice day.