This one is pretty easy. You can link a few achievements here. I also got Stunning and Headcase as well, just on this level. Make sure to load on Easy.
For Headcase, load "Grunt Funeral" skull before you start.
For Stunning, follow the other guides here, it's the perfect level. I killed a grunt, took his plasma pistol, and then charged it and took out a grunt on a ghost, then meleed him once he was stopped (has to be within 4 seconds).
I then took the Spartan Laser fully charged to each wraith, and also picked up a rocket launcher with 6 shots in it. I pretty much drove the ghost, used it for unlimited ammo, and when I saw a wraith, jumped out and took one of the two heavy weapons to it. Either on easy will take it out on one shot.
Once you hit 6/6, achievement pops. However, for Headcase, make the final jump.