Thanks a lot for your suggestions. Yes, your points are totally clear. We have got similar type of requests from other people too. So we have taken it into serious consideration and we will try to provide these features in our future releases.
For category sorting, we have already given you a fix here: https://duogeek.com/support/topic/duofaq/ and I hope it helped you.
What do you suggest for multiple sorting? Do you want to set sequence in the questions listing page? You can set the order in the questions creation page now. Is there any better way you can suggest?