What are the rules of teleportation?

Teleportation skills like Lightning Flash, Blink, and Shadowstep* are extremely convenient and useful, however I oftentimes find myself falling victim to unspoken (or non-specific) limitations.

The known limitations are:

Teleport
Most skills only teleport the caster to locations normally accessible without jumping or falling. Attempts to teleport across a gap or between two elevations usually results in the caster moving to the edge of the current plateau, if the 2 platforms aren't directly connected or the walking distance is too far - in general, the teleport will work if the game can path a non-jumping route to the target location that is not too long.

Also:

Shadowstep
Shadowstepping allows the player to move vertically as long the position can be reached normally by moving on the ground without jumping. Trying to shadowstep up or through obstacles or across gaps will cause you to shadowstep to the edge if the target location is too far or unreachable by walking.

What exactly are the limitations?

• How long is too long?
  • If there is a flat surface aside a ramp, how far is too far to teleport from directly beside the ramp to the top of the ramp?
  • Does it matter the total distance of the walkable path is or is there a radial limitation from the players position to the "turns" of the path? In other words, would a long but thin path curving above the player stop the teleportation?
• Are there technical limitations?
  • Are there any issues with teleporting from prefabs (eg. rock formations, broken walls in WvW) to terrain like other games?
  • Are there locations in the game where teleport just doesn't work as an exception?
• How are gaps handled?
  • Why can I teleport across from the ledge outside of Clock Tower in Battle of Kyhlo to the capture point and back? Does teleport work across gaps like a Mesmer Portal? Or is there a walkable path between these two points (likely not the boxes near the window since you need to jump on them to get out)?
• What are the consequences of failure?
  • Does Lightning Flash still do damage to the selected location if the teleport is unsuccessful?
  • Will Shadowstep still allow the user to return to their previous location if the teleport is unsuccessful?

_{* Note: this question is only related to skills that work similarly to the ones mentioned. So, the limitations of Portal or Spectral Recall would probably be out of the scope.}