Floating windows
Position, size, opacity
Every window remembers where it was and how big. Opacity is set once for all floating windows.
Moving and resizing
Like any window: drag the title bar, resize at the edges. The next time you open the same note, the window is back where you left it.
Opacity
The three-dot menu has Transparency, shortcut ⌥⌘T. The slider runs from 55 to 100 per cent and applies to every floating window. The main window is always opaque.
Keep in front
By default a floating window sits above the app you are working in. If you want it above everything, turn on Keep in front in the menu.
NextTyping without losing focus