I'm relatively new to TI, but have heard all of these terms used in various books, videos and the workshop I attended. The terms that worked for me were the following:
1. "Focal Point" - I'm not sure why "stroke thought" doesn't do it for me. Maybe because I think of "stroking" with my arms. Many of my recent focal points have involved streamlining my legs, getting proper hip rotation and breathing without losing tempo. For cases like this, "focal point" seems more appropriate to me.
2. "SpearSwitch" - Captures the idea of spearing forward. When I do this drill correctly I feel my body spearing toward my target.
3. "ZenSwitch" - I understood from the workshop that one of the main purposes of this drill was to reduce tension in the recovering arm and enter the water at the correct time. I had a very hard time getting used to doing this drill because my hand was not relaxed and therefore created a lot of drag. In order to get the drill right, I had to let my hands be in more of a "Zen state", yielding to the water rather than trying to force my arm into it.