Hello Don,
there is a "Drag-and-drop matching" component in the tracker in the CONTRIB project so I think this is the place to post bugs
The problem is that as I am not the "official" maintainer of this addon, I am not automatically notified of new issues created.
Another problem is that I know nearly nothing about javascript so if the problem is in this area of the plugin, I need to find somebody more talented to fix it !
If I look at your 3 reported issues:
#1 is definitely javascript and/or CSS so I am unable to fix it myself
#2 is unclear to me, I was not able to reproduce it. Can you upload a screenshot ?
#3 is also not reproductible for me, I was able to create a ddmatch question with 2 items on the left and 3 on the right with no problem during attempt. But there is an issue with items on the right that don't have a matching item on the left (subanswer with an empty subquestion) because images are not displayed this is issue CONTRIB-4015 and this is in fact a problem in the check_file_access function in question/type/ddmatch/question.php. I will fix it ASAP.