You can usually export out the same codec that you're editing in, but it depends on which codec you are using? What format do you want to output?
Editing long GOP source material like this H.264 source will ALLWAYS result in a generation loss. There is no way around it. However, if you export with the right codec and the right bitrate settings you can minimize the generation loss to be hardly noticeable. But, it is important to export as few times as possible. Of course 5 generation losses will be far worse than a single generation loss and if you want to get the best quality on output, use the Maximum Render Quality setting. It will take 2 - 3 times as long but you maintain quality better.
Thanks again, while not the answer I hoped for it is still the answer
So, new question!
What is "GOP"?
I've changed those settings as you suggested, thanks very much for your help AGAIN!
One thing to consider with Export, is what do you plan on doing with the resulting file?
If, for instance, you need to get the Exported material onto an iPod, you would work within the restrictions of that medium, and set your Export to match that. If you are going to BD (Blu-ray Disc), you would work within the specs. of that medium - and so on, and so on.
What is your intended delivery medium?
If it is to exactly (as close as you can) your source footage, except with the edits and additions, then sticking with the same format/CODEC and size settings will get you what you need.
Let your needs dictate your Export settings. Remember, you can Export to many different settings, so you will not have to do any conversions, of the original Export.