v0xyl

Can confirm, although this only appears to happen when the cursor ends up being on top of the "FOV Effects" button once the menu opens up.

Can confirm. Additionally, this seems to be the case for jumping from any height at or above one block so long as the user is shifting for 1-2 seconds before hitting the ground and isn't interrupted by fall damage, water/lava, or cobwebs (potentially other things, though I haven't tested much).

This is intended as player coordinates (which are what you are placing the block relative to) are taken from the position of the player's feet and have nothing to do with crosshair orientation.