1) I'm not really sure this is a bug/glitch but the behavior is really wired
First do a tower like this one
Then go in the corner and hold jump + sneak. Is it "normal" to travel at ~11nodes/sec ?
2) If you are on the edge of a node (without sneaking) you can't jump.
3) Same as 2) you can't jump in this configuration
4) When you are falling and then press sneak to land on the edge of a node you don't take damages (easy to test with the tower)