If one of your players falls down on your turn, it's a turnover.
If you fail to catch a pass, or fail to pick up the ball (or basically make the ball hit the pitch in any way) it's a turnover EXCEPT if you fail to catch a bouncing ball that is not the result of a pass (IE, you knock a player carrying the ball over and it scatters to you).
I think that's all the rules for your examples.

Someone else will fill in anything I missed.