Normal for a Black cat, they are far more intelligent and willing to do things than others. She is a ratter and will hunt for you if you call her. She'll will always want to see what is in boxes no matter the size. You will also note that she has chosen you as her master not the person who purchased her or wanted a cat.
There is a down side to that cat though. She will attack you without provocation and you will have scares to show for it.
Do her a favour though and don't use foil balls they damage their teeth and gums on them. Go to a pet shop and get a little toy mouse to chase after.
Uhuh, I think it has more to do with the breed than the colour dude :).
I have a burmese, same thing, she will fetch and return (to my lap, no drop in lap, no more throw) and she aint black (she is Lilac). Rolls over for belly rubs, and nibbles (A little nibble on the back of the hand which may hurt a human is actually them showing love, they have nerve endings quite deep under their fur so they need to bite quite hard to give a sensation but it's actually a cat kissing you).
Agree about the foil though, we just bought a load of Leather mice and she loves them.