This is an old thread but I ran into the same issues 3.5 years later!
1. Regarding the date-format.default issue:
The Folder Properties page is currently being fixed as I write: MNT-14060
The Version History page has been fixed from 4.2.3 onwards: MNT-11717
2. Regarding "what affects the modified date and create date", I recently did a little analysis incorporating the latest configurables. I thought I'd share it here before I find a better place to put it.