On my PC, if I select "edit in photoshop" on a raw photo, it automatically seems to open a TIFF version in Photoshop. Please can an option be added (or a preferences setting) to allow files to open as Raw files in Photoshop instead
Lightroom has highlight clipping too. It's those triangles in the corners of the histogram. Click on them (or hold your cursor above them) to see the pixels in the image turn red (highlights clipped) or blue (blacks clipped).
Not sure if there is a setting I need to change to enable that, but I can't see those triangles you're referring to. Those are what I use in ACR, but I can't see them in Lightroom. To emphasise, I'm using Lightroom CC 2018 (cloud-based)