As for the black, it is probably just a little bit of dried blood. It's not uncommon for the vaginal progesterones to irritate the cervix a little and cause some streaks of blood. I had some brownish discharge at some point when I was on crinone. But if it's solid black, you might want to contact your RE just to make sure.
Also, and a little further down the line, I started getting little gushes of watery discharge. It almost felt like I peed a tiny bit. Very weird feeling. I remember someone else on here said the same thing, so just in case you experience it too, don't worry. It's normal.
Oh, and my IVF was successful, so all the weird side effect certainly didn't have a negative effect on my chances. Best of luck with everything!