MM you have them mixed up - there is a test for frame, aka LWO. There isn't a test currently for Splash.
There have been horses that have tested negative for frame that have blue eyes. However, until a test is available for splash, there is no way to determine for sure if the frame horses with blue eyes aren't carrying splash too. At this stage, blue eyes are thought to be caused by both.
I don't know if there is a technical term or not...we've always called Dynasty's his boo-boo :) I think they are pretty cool myself! He's yet to pass it on to one of his babies, I always kinda hope he will though!
Not sure if anyone answered this yet, but I believe the term is partial heterochromia. I could be mistaken, but Im fairly sure I'm not.
My friend's sorrel paint stallion has a half blue eye too.. it's really neat to look at. There's also a gray walking horse with a half blue eye. We've got two at our barn! Haha, they must not be TOO rare. I also had a black/white paint filly with two blue eyes, but one of them had a brown smidge so it wasn't completely blue.