When I tried the 'Select by pattern' dialog, I presumed that it was case insensitive by default, similar to when you type a name in the file pane or search in catfish, but as it is not I would suggest that it be made case insensitive always or alternatively have a checkbox in the dialog to notify the user of this option.
On second thought, using PCRE would cause confusion for most use cases... It should be a separate feature, and so it's an separate issue. I should only patch for case insensitivity then.
I dont think it is worth to have xfconf setting for it. Wait until someone actually asks for it ...
I am asking for it, as I would like to use it always with it disabled.
IMO a matter of taste. No need to invest more time into such small details.
Not of a matter of taste but something that would be described in HIG. Even the 'examples: ...' should be removed and be put as a tooltip or something else as it also isn't good design.