when you start premiere, select New project, but dont choose from those presets, but choose "custom settings" and then in "editing mode" choose "Video for Windows", then you can create your own resolution (and dont forget to choose "Square pixel" aspect ratio)
to get black corners you can copy the video to another layer, decrease brightness and apply a mask on it OR another way is to create black corners in photoshop,save it as .psd and then import only the layer with dark corners
EDIT: too late
