How to reverse order of pulldown Views Exposed Filter showing taxonomy terms reference field
You should give Entity Reference a go. You don't need to use the autocomplete widget. The standard dropdown list is sufficent. Just create a entitiy reference, type "taxonomy term", select your vocabulary, set to sort by "A property of the base table of the entity" and select "name" and "descending". This should work...

If you need to add new terms on node creation, you could try Entity Connect module. The module will allow you to dynamically create and edit some entity types (e.g. taxonomy terms) which should be referenced into an Entity reference field.