tiff 32 questions

[ilovedividends]

I'm playing with some more stainless steel again and had never exported as tiff 32 before to play with exposure and possibly retain some of the brush strokes in the blown out areas.

When I am rendering a file in tiff 32 w/ transparency checked, I then open the file up in photoshop CS6 and I have a background and don't know how to remove it to get the image as a transparency.  It appears there are very limited things you can do with the tiff 32 so are you supposed to copy and paste the post-exposure image into an 8bit file?

I looked at the CAD mouse webinar again, but that version of PS doesn't look like it is handling the tiff 32 the same or else I am just an idiot which sometimes I am