1. Still works as far as I can see, same way as I remember it always working. Command T while in an alpha will transform in the same way as a selection will transform. Same logic, probably the same code
2. This was replaced, with more intuitive behaviour, I have a vague memory . "Deselect path" is now available by clicking in an empty area of the paths panel. This is still Actionable and will record as "Deselect path"
3. What path manipulation options are not available while in Quick mask? Everything, pen, direct selection tool works. Only thing that doesn't is Free Transform path - I can't remember if there was a point where this would take the active path instead
4. "Option to turn off palette docking" not sure this was ever possible. On this one I agree with you, CS4 does not have the best interface in some respects. Particularly annoying is the auto docking of panels when you are dragging them around. This is slightly clunky 'Macromedia' style interface decisions, and unfortunately I think, no longer controlled by the Photoshop engineers alone.
1. You're on correct # 1 - this wouldn't work earlier today -must have been some form of pilot error -my bad.
2. If Path palette has many paths, there is often no blank space to click/de-activate path. Turn-off Path button existed years ago -why not simply restore?
3. Can't TRANSFORM paths in quickmask as I said. Why not? -useful tool.