Photoshop :: How Simple Tools Be Used In 32-bit Per-channel Images

I have just begin working with HDR imaging.  I am using it for what it was designed for.  The subject of the photograph is a creek, looking straight across the creek to the far bank.  The creek and the far bank are in bright sunlight.  I was in woods, and deep shadow, when I took the photograph, and so the foreground is very dark.  I converted the image to 32 bits/channel when merging it into HDR Pro, and used ACR to tone the final image.  All of that worked very well.
 
But when I wanted to make some final little adjustments to the image, I found that I couldn't!  I wanted to select a color range, but the Color Range option was grayed out.  I tried to use the magnetic lasso, but a message box popped up saying that I couldn't use that tool in 32-bit images. 
 
I don't understand this limitation.  32 bits are supposed to be best for HDR images, but I can't use simple tools to edit the result? And then when I switched to 16 bits, it seems I have to merge the channels first, but that loses all of the smart filters and other history that I had when working in 32 bits!