For the last two or three days, some of my KudoZ questions are disappearing from the KudoZ list. Some even don’t show up. The responses are all in my mail-box, so I figure at least some people are able to view them. I’ve checked the “admin actions” at my profile, nothing whatsoever.
Can there be an “admin action” by site staff without notice at all?
No, there cannot be any admin actions without notice; and there really are none in your profile. Moreover, in case you get answers to your questions, this means that they are visible to others.
The best way to check your questions is looking at "KudoZ activity > asked" in your profile; in case you don't see your questions on the general list of questions it is most probably due to some filters; please take a look at the settings box in the upper part of http://www.proz.com/kudoz/ page and make sure there the language pairs and fields are "yours", and that there are no keywords or other settings restricting the search.
In case everything is OK with the settings, you may want to clear cache in your browser and reload the KudoZ list afterwards.