Here is an illustration of some conceptual work on the question bank interface. The idea is simply to have all 4 functions - questions, categories, import, export - on one page. Here the last three functions are pushed into blocks and added to the questions page.
This is just a rough start but for what it's worth, here goes.
The questions categories is currently enhanced with two bulk functions - add categories ('import' in the illustration but should be 'add') and delete categories.
Adding categories is done in the custommenu style so you can add a hierarchy by one go.
Deleting categories uses a swipe left gesture for marking categories and then a click on a delete button that appears for that purpose, to delete all marked categories.
Then there is import and export each one in its own block so as to benefit from the block builtin collapsibility for better usability. The blocks use the original question import/export forms and processing. For my purposes I slightly tweaked these forms to change the file format radio buttons to dropdown to save space. The latter is a bit more important for the import form where I also added an editor which allows me to import questions to html formats (if supported) by entering them into the editor in the designated format.