Thanks to all.
For stroke zero-to-full-length, Build modifier is clearly the simplest.
For sliding a stroke along a curved path (similar to 3D Curve modifier), there are several ways to redraw or edit the stroke. I was using extrude-head + delete-tail (with cleanups) since this seems easiest and most accurate. Of course a full draw at a new position (classic method) or other edit operations are also possible.
Putting this one to bed for now.
