Hi,
I am new to film making. I shot a theatre group rehearsing for a documentary. I just realized I shot in every single possible format (1440/1920/720, you name it). Questions: What format should I choose for putting the documetnary together? Any suggestion for an ready explaining the different formats? Still can't understand the differences. Thanks!! and Please HELP!!!!

the format you should choose is the one that you have the majority of. in other words, if the majority of your shots are in 720p, then make it all in 720p.
the difference with the formats is the density of the pixels. as the numbers go up the more dense the pixels are and the more information there is in the shot and therefore a much more clearer picture.

Also, P, progressive, looks more like film than I, interlaced, does. So if you want a more film like look I would go for the 1080p. You always want to shoot in the highest possible definition.

The higher the definition the more information (by information I mean detail) is recorded and the more latitude you have to work with when you want to change the exposure, look, etc.

actually P and I does not make the video more or less film like. It's purely how the videos are being outputted. In an Interlaced video, either the upper or lower field is generated first, then followed by the other field. This is usually fine for movies where there are very little movement. Progressive on the other hand shows both fields at the same time therefore better for high action videos (sports, action movies, etc).
You can shoot in 1080i and still make it look nice. As I have said in my previous post, set your project at the resolution where the majority of the formats are in so that the quality will look much more consistant that throwing in the highest quality possible and suffer a heavier inconsistency in quality.