"How should I store my loaded Hi Power at home? Cocked and locked? Condition 2 or 3? Should I keep it at half cock with the safety on?"
The answer depends upon your personal situation and if you intend it to be a self-protection weapon.Frankly, I keep my Hi Powers and other single-action automatics in but two conditions.
If loaded and outside the safe, the pistol has the hammer fully cocked and the thumb safety engaged. If unloaded and in the safe, the hammer is all the way forward.
This Hi Power went for over a decade with the hammer at full-cock unless the gun was being fired! It used the standard 32-lb. mainspring from FN. This gun and others I've used in the same manner have never exhibited one iota's harm or spring-weakening from this practice.
I can think of no compelling reason to store a Hi Power with the hammer forward or at half cock with the thumb safety engaged.
Some folks do opt to keep the gun in "Condition Three" when not being carried, but still being used as a home defense weapon. The reason I've been given is that if they wake from a deep sleep, they prefer to have to rack the slide and chamber a round before the pistol can be fired to insure that they don't do something unintentional while half asleep with a cocked and locked Hi Power.
You decide if that works in your personal situation.