Hello Lucy,
Not all the settings all video can have are covered in the Easy Setup for fcp 7. You can, however, adjust your timeline to match the settings of your video. The Easy Setup is only a preset that will grab a default setting for any sequence you create within that project.
The Easy Setup preset you selected was based off HDV material, which is Anamorphic, and thus comes out as 1440*1080, which stretches to be 1920 when the Anamorphic flag is ticked. (turning 4:3 footage into 16:9 footage, essentially)
The easy way to adjust the timeline settings is by dragging a clip from your rushes into your timeline. FCP will ask if you want to adjust your settings to whatever your footage is exported as. This usually works fine, but it never hurts to know which setting is what, and where to adjust them.
So to set things up manually, we can create a new sequence, and set it up by going into the “Sequence – Settings…” menu (default cmd-0), which will pop up a menu allowing you to adjust your timeline.
In your case, where your rushes were made ProRes 422 1080i50 the settings from top to bottom would be
Frame Size: HDTV 1080i (16:9)
Pixel Aspect Ratio: in the case of 1920*1080 video almost always Square Pixels
Field Dominance: You’d have to check, usually Upper Field First (the ‘i’ in 50i means interlaced, which means the frames a split up into two fields with interlacing image lines. One of these fields is drawn first – either the odd or the even numbers, followed by the second field in the other 1/50th of a second. You can check this by right clicking a clip in your bins and reading it’s Item Properties)
Editing Timebase: 25fps – your footage is 50i meaning 50 fields per second, which makes for 25 full frames per second.
After setting this up, your footage and timeline settings should match, which will help with rendertimes and exports. If set up properly, your timeline should show no colored bars at the top (meaning the footage does not need to be rendered as the timeline is already in the right setting to play the footage dragged onto it)
Hope this helps!