A question that might help me understand. I guess everyone knows that I am a newbie. Does the sequence in itself affect the output? My output is to be PAL, widescreen, so when creating the sequence, that is the setting I was using. The cameras I was using were Sony HDs. Should I then be using Sony settings for the sequence?
Typically, one would edit in a Sequence matching the source footage. If source is HD, then edit HD. Maybe you will want to keep an HD copy of the edit? If you edit as SD, then that's the best the "master" export could ever look, being SD quality. I understand in this case you want to deliver SD (PAL), but no reason not to edit as HD and keep the quality up through that process.
You very simply then Export to whatever format you want when done, SD or HD. Maybe you will want to put an HD copy on YouTube later, but in any case, I certainly prefer to keep an HD "master" copy of finished projects, from which I can later export to whatever format may be needed for various purposes. Don't limit yourself to SD quality when editing HD clips.
There are no Sony-specific Sequence presets. You just want something that matches your footage, doesn't matter what the preset is named. So if the source is "1080i" at 25 frames for instance (might be called 50i) then use a 1080i25 Preset. I don't know if CS5 has these options, but since CS6 at least one could right-click on a clip in Project Bin and choose New Sequence from Clip or drag a clip onto the New Item icon. Or when dragging the first item onto a new, empty timeline, Premiere should ask if you want to adjust sequence to match the clip (if it doesn't already). But again, not sure if CS5 does all of that.
You can almost always find a good HD preset under the AVCHD heading, whether source is 1080i, 1080p, or 720p. See image for 1080i25 option. I don't know for sure if your footage is 1080i or 1080p. Right-click a clip in the Bin and check Properties to see what it reports, and make sure specs of sequence match specs of video (frame rate, frame size, pixel aspect, field order).
As Ann mentioned, the 1440x1080 clip uses non-square pixels (called Anamorphic HD). Create the sequence to match the full-quality 1920x1080 clip and when you drop the 1440x1080 clip into that timeline, it should appear full-screen, Premiere handles that for you.

Thanks
Jeff Pulera
Safe Harbor