On subject of empty panes, this is what I found:
It's a known quirk of workspaces.
When you modify a workspace, Premiere remembers your changes. That's why the Reset Workspace command is there.
When you have x number of sequences open, the workspace remembers that those panels were open. Since when you open a new project the previous workspace is used, you'll see x number of empty timeline panels open.
Vince Becquiot
Kaptis Studios
San Francisco - Bay Area