Two different gun law books from attornies in Florida and New Jersey offer slightly different perspectives. In New Jersey, Evan Nappen wrote that after an S/D shooting, the shooter should tell the cops something to the effect that, "Officer, I know this is a serious situation and you want to investigate, but I need to speak to an attorney before I answer your questions."
New Jersey's version of the "Castle Doctirne" is an Affirmative Defense law. It means that the state can prosecute you for killing someone in self defense, but if you can convince the jury it was self defense, they must find you not guilty.
Florida attorney Jon Gutmacher offered a different perspective, but this is tempered by the laws in Florida. In Florida, if you kill someone in self defense, you're not going to be arrested, you're immune from prosecution and civil suit. So in Florida, Gutmacher says this:
You're the victim! In order to make sure the officer knows this, something akin to the following statement is extremely pertinent:
"Officer, I was attacked by this man, and thought he was armed. I was in fear for my life, and was forced to shot (sic) him in self-defense."
Once you've said this, and you're sure he's heard it -- you don't generally want to go into any specifics until after you've spoken to a really good lawyer who knows this stuff.
Sounds like good advice to me.
I would not clear my weapon. I would also not put it away until I was certain that I was no longer in danger. Whether you holster it or put it down where you can guard it and get to it quickly depends on the situation.
One thing I would not want is to be standing over a dead guy and holding a handgun when the cops show up. There would be enough problems without the police misinterpreting what happened, or deciding that I was the bad guy and firing.