I've noticed that if I add

Keyword Property Dummy Auto

to my script, and the property name and type matches an existing form. That when I add the property in CK it can "Auto-Fill" the value accurately.. Neat!

Q1: Does this mean that if I avoid adding a value all together in the CK, that Skyrim will find the correct property on the fly?
(I ask because i've seen some vanilla objects that have left properties blank.)

Answer: After testing, it seems that Skyrim doesn't auto fill, but http://www.creationkit.com/GetFormFromFile_-_Game can do (sort'of) what i was talking about.

Q2: So if i want to package up my edits to a vanilla script as a .bsa.. but i haven't needed to edit any objects to fill the properties, do i need an esp?

Answer: Turns out you do need an esp even if it's blank. So long as it's enabled the bsa will be.. I guess a lot of texture replacer mods already do this and im just a bit slow on the uptake

Actually, you can piggyback Update.ESM. Name your BSA 'Update - Neon Waffle Irons.bsa' and it'll auto load by virtue of nomenclature without a dummy plugin. Alternatively, you could add it to one of the archive lists in Skyrim.ini

Ahh, very clever!