I recommend ignoring update requests when they pop up. It’s not just Boost, I’ve seen so many of those kids of ads now that I just go check for updates through the system.
Flashlight, water purifier, respirator, and rifle (I assume with required things like ammo).
Nobody said how this plague spreads, for all we know it’s in the water or Airborne. Flashlight for scavenging and because it’s far more important to know if that’s a pile of scrap or a Zombie than it is to stay super stealthy. And Rifle gets you everything else you need.