Various configuration questions, mainly about folder tabs

No. The drive-letter can be turned on but that's it, AFAIK.

If you turn off Preferences / Listers / Folder Tabs: Use Visual Style under XP/Vista then you can configure custom colours under Preferences / Display / Colors and Fonts.

Not that I know of.

The only tab-size options are those in Preferences where you can set the max size or tabs to use a fixed size. There's no option to prevent them overflowing.

(If you regularly open that many tabs open, maybe it would be better to use something else instead, e.g. a menu of paths/favorites or tab-groups.)

When going up or back to a folder the same lister has already displayed, yes, but not when reading a "fresh" copy of a folder (i.e. navigating any other way).

Use Tools -> Find Panel instead of the old standalone Find window.

Yes, see the second post (my reply) in this thread: Create a new (empty) file.

BTW, please ask unrelated questions in separate threads in future so the forum is easier to search.