I didn’t fire it. It wasn’t loaded. I just held it to see what it would be like.
I was at his house,not at a range.
Such a belief should never affect how you treat the gun. There are many sad stories which contain the statement, "I didn't know the gun was loaded".
Were you told to assume it was loaded until you cleared it yourself? That’s rule #0. See a few comments up for rules #1 to 4.
Stance? Personal preference matters. I use a modified Weaver. (Just Google it for details.)
Doesn’t matter where you are. The first rule of gun safety is to ALWAYS, ALWAYS, ALWAYS treat a gun like it is loaded even if it clearly isn’t.
That means you don’t wave the gun around as you are talking or point it anybody in general. Point it away, up or down from everyone else. Even when cleaning it!
You always keep your finger off the trigger until you are committed to firing it. And before you fire it you should have a good idea of where it will go if you miss or it over-penetrates.
Once you get that rule down and in your head and practice it consciously all of the other gun safety rules will be a piece of cake!
Have fun and stay safe!