Suggestions, there may be better ways!
Q1. Select one or more images, Press F2
If [Date - Filename] pulls in the wrong date, create a Custom rename such as [Custom Name - Filename] and type the date as the "Custom Name" in your wanted format yyyymmdd.
Q2. Create folders with required dates (Right-click on a 'Master' YYYY folder), Drag images with corresponding date to its folder.
Re-structuring: probably can't be done (there is no auto-restructuring feature in Lr, and no functions so plugins can do it).
Re-naming: what wobertc said..
Note: restructuring can be done via SQL if catalog not open in Lr, so it's possible there is a utility app that could do it, or a plugin which operates on different (non-open) catalog.. - dunno if such things exist.
Thanks, the rename step is perfect, I hadn't seen that bulk-rename option before.
Thanks, that's what I figured. I can do it manually, as wrobertc suggests, though with five thousand images spread across 20 years, it will be a bit tedious. (Easy if I want only one folder per year, but more tedious if I want subfolder per month.) But it'll do.