I'm not sure about the hidden packages thing, although it did happened to me i think. (or I just COULDN"T find the last one...)
45+ points on shooter, it's the minigame in the Downtown Ammunation, just walk to the back of the shop in the door, and stand in the pink marker. the mission starts, and you just have to get 45 points.
just shoot the bodies of the 2 closest targets from you. don't shoot the heads. now concentrate on the 3rd one, keep on shooting it and you'll have 45 points in no time