Is there a way to render a sequence to disk and also view the frame buffer like most renderers. Or render to Mplay and save each frame to disk when each one finishes?

I know you can render to Mplay and save afterwards, but the reason I ask is so I can see the progress, and in case of computer crashes during rendering.

I don't think there is right out of the box. You can always write a script to bring up the last frame if you are ambitious. I just use the file browser from the OS to inspect the folder I am rendering to. Then I can see thumbnails of previous frames easily. If I want to view one up close I send it to an image viewer.