[ul][li]0. (Please ask one question per thread.)
[/li]
[li]1. Folder Formats: Quick Guide
[/li]
[li]2. You shouldn't normally need to change tabs before ejecting a removable device, and just changing the active tab, while the tab for the drive is still open but inactive, won't make any difference at all.
Ejecting a USB drive should work even if the drive is displayed in a folder tab, unless they are mounted as non-removable (probably not relevant here, since they would not show up in the systray icon then either). Or unless another program or operation has the drive locked (in which case whether or not the tab is open is irrelevant; the drive will still be locked by the other operation). Or unless the tabs itself is doing something with the drive (e.g. loading thumbnails, but that would continue in the background even if you switched to another tab, unless the tab was actually closed.
So you should not need to do anything at all for 2. Normally, you can just eject the drive and not worry about any tabs still displaying it.
However, if you do need a way to close all tabs showing folders below certain drives, you can use my CloseAllTabs command.
[/li]
[li]3. Make a backup of your configuration first. Then you can restore that backup later if you want.
The Dear Opus config mostly moves commands around on the menus and toolbars, without adding much new functionality to what you get in the Opus 11 default toolbars (at least from the last time I looked). Some people prefer the different layout, so feel free to try it and use whichever suits you best, but also remember that you'll be making it harder to understand the manual and other documentation which is based on the default layout. You may need to search for commands in your menus and toolbars if you switch to a custom set.
[/li]
[li]4. It's probably best to start a new topic for that, with specifics of what you want to restore (current folder? folder format? possibly other things I haven't thought of) so we can discuss how to do that.[/li][/ul]