Class Hack Question

So there are a few class hacks out in the Modern Warfare 3 forum. Those that allow you to get an UAV or any other deathstreak as soon as you switch to your secondary. So I have 2 questions about that. I'm using Hollow Points for secondary. So first, if you switch back to your primary, does the deathstreak remains there for you? Or do they only work with your secondaries? Also, if you kill an enemy with that deathstreak on, do they get to see the icon anywhere on the screen during the killcam?