I have a 16 GB iPod Touch, so I'm just answering out of experience...
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Lets say, I leave it on all day connected to my home internet via wifi uploading things to youtube, how long would battery life last?
That depends on what you're doing; if you're specifically asking about uploading vids, I think it would last a good 10-12 hours unplugged (as long as it was completely charged when you started, of course).
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Could I keep it plugged in?
Yup. Whether you use a dock, or keep it plugged in to your computer, it's fully functional while you're charging it.
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Can it upload other types of files to other sites? Like, .rars to megaupload?
I know certain sites allow you to upload pictures from your Touch, but I don't know about other types of files, like music or videos...
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Can it run p2p programs (like utorrent)? Or do I have to mod it to do that?
I really don't know. But I did Google it. Maybe something like
*this* will help...?
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Do I NEED to use itunes to put music and video on it? Or can I just plug it in via usb and have my computer copy files to it like it is an external hard drive?
I don't think you need iTunes; copying files straight to its main folder will probably work fine. (I think my friend does that, I could ask, if you really want...)
Hope I helped. ^^
This post has been edited by Jahnavi: Nov 16 2009, 3:45 PM