Glad that you figured it out. Perhaps Reference Line Point should be the default selection in the Snap Origin drop down, as it would be the most frequently required behaviour.
There are some really cool and powerful snapping options in the newer version of the toolkit. If you have not seen the video on Snapping & Locking Framework , I would suggest that you take out some time to go through it, at least once.
Yes, I am planning to include these features. Do you have any short and simple videos that demonstrate the functionality?
As I mentioned in one of my earlier posts, the plan is to first refactor the Flexi Edit to make selection of points and segments consistent (this is mostly finished now) and then, maybe, implement tools to draw primitive shapes (like circle / ellipse and polygon, to start with) . So maybe I will work on the things you mentioned after these items are taken care of.
But first of all, of course, Configurable Hotkeys… it’s missed by many users 
And just btw, the tool need not be “the best of all”, I would be happy even if it’s just a robust and useful tool, helping the creative people out there. The frustration one experiences when something doesn’t work in an intuitive way, is well known to me. Fortunately, with Blender Python APIs, the user is now not so helpless anymore