I am a poor student of maritime regs & jurisdiction, but I know this:
Blinking white/strobe - as you pointed out means distress, and only that. Paddlers who use a blinking white inadvertently cause a lot of confusion and create hazards. For example, a vessel trying to aid may actually come in too close & swamp a kayak. In monitored waters a kayaker using a blinking strobe will trigger unnecessary distress calls on Channel 16 & waste others' time in responding.
Stationary white --> vessel to another vessel. It lets them know we are out there which is Job #1.
As far as where to display the stationary white light my belief is if it ain't lashed to the boat or attached to you it ain't secured. If someone is relying on a suction-cupped light they will sooner or later be disappointed following a wave or capsize.
Whatever we display on our boats, our heads, etc, does not replace a strobe light w. a minimum visibility of 1/2 mile lashed to our PFD as the absolute fallback esp. if we are in the water and separated from our boat. That is what the USCG and other SAR personnel will be looking for.