[FordGT90Concept]

You really need an anti-materiel rifle to clear the quarry (it's one of the last things you should do in the game). Also, use the hills to your advantage. They have to take the long way up which gives you time to unload bullets. Only aim for their head--everything else is a waste of time.

Boomers is kind of tricky. What worked best for me is going through the house rubble in the nude (don't want the armor to get damaged). You'll have to jump and duck your way through and eventually, you'll get lucky.