As an avid coffee cup warmer user (for coffee) I doubt that it will keep the pyrex cup hot enough.
I think an electric burner like this one would do a better job, but haven't tried it.
$19.98 Elite Single Disc Electric Burner
Walmart.com: Elite Single Disc Electric Burner: Appliances
I did some experiments last night.
On a 5.25" aluminum 4 cavity senko mold, the only time I could get a dent was when I let the pour cool longer than 3 minutes before de-molding.
I can't get a real good look at the color from Yamamoto's catalog, and haven't seen them in person, but it looks a lot like a color I mixed the other day using pearl blue powder and marine blue colorant. I didn't use any glitter though.