For (1), a similar issue was logged recently logged but you can add to it:
https://github.com/horosproject/horos/issues/635. On my Intell macbook and M1 mac mini both running macOS Big Sur 11.2.2, I can reproduce the drag and drop issue but things seem to work fine using the Import button.
For (2), please open a new issue with a screen shot showing what you see, if possible.
Todd Jensen, PhD
Jensen Informatics LLC