thanks for your feedback! You can access the latest folders via the drop-down list at the Directory field in the Tag Panel. By choosing one of the entries, you'll navigate back to one of your previous directories.
Tabs and multiple instances are not planned at the moment, but:
For easy copying of data between albums you can also load both albums to the file view. Instead of changing the directory via File > Change directory... you can also add another directory to the file view via File > Add directory.... This also works via drag&drop from Windows Explorer (or your favorite file manager) while holding the [Ctrl] key down.