How to get behavior of menu that points to a drive

a) make the menu only show selected folders from the e: drive? (I can't think of a way to make filters work because there's not really a pattern to distinguish between the ones I want and don't want to show)

You can just hide the items you don't need. Right-click the item you want to hide and select "Hide" in the menu.

b) make the folders listed in the main menu not expand into submenus when the mouse is on them? And have them open in Explorer when they're clicked on.

Right-click the menu item and remove the check mark from the "Expand folder".

PS. Maybe the better solution is create the normal menu with the shortcuts to the folders you need?