They make a deglasser that supposedly strips the die off and then you can redie it the color of your choice, I've never tried it. I believe the company is frieburg or something along those lines. They make all the leather dies in the black/yellow containers.
Nope. Someone asked that question on Facebook the other day. No such thing.
I've never heard of a lightening product. The best you could do is leave it in the sun, but that will take time (weeks to months) and only slightly bleach the leather, and may damadge it.