I only use live view to compose a landscape shot. Liveview is not great for action shots, i don't think you can change that. It has to do with flipping the mirror up so you can use liveview, take the picture then recycle the mirror again
Well, the view finder is inaccurate for focus when using an old Pentax 50mm manual lens and when you're shooting over the top of people's heads in a crowd, there's no other option. It just sucks when it goes black for over 2 seconds. I know the mirror is doing things, but I didn't know if it was a completely physical reason for the blackness, or a programming function.