Pívot shoe and coil support

Are you referring to the 15-255 support? If so, I've never really noticed a difference in depth between this and the 15-259. If there is a difference then it is negligible. I've never encountered an issue when installing this hardware.

To be honest, I can't imagine a scenario where the cover being smaller than the shoe would ever make an impact on its function. These screw directly to the window track, so it's not like they'd be loose in the frame. And if you're only talking about a difference of 1/32" (if that) then I don't think there's any reason to worry.

It's ultimately up to you, though. All I can tell you is that the 15-255 was specifically designed by the manufacturer to work with the 15-259 shoe. They are built from the bottom up to go together. There is no alternative.

Yes, that is correct. The pivot shoe does not push into the coil support. During normal window operation, they probably won't even come into contact unless you raise your window as high as it will go.