Okay, I'll pay more attention to the organization of my thoughts.
Format: As far as I know, everyone who animates with a DSLR uses .jpg; I do. It's a standard file type that any program can work with, and it doesn't take up to much space. For the most part there really isn't any reason to use anything other than .jpg. When it comes to RAW, especially for video, the main reason for using RAW is to correct for factors in your shooting environment that are out of your control. The thing about animation is, you control the environment; so unless you want to do some really heavy color correction, you don't need RAW, and even then I'm not sure it's necessary, I don't know much about after effects and advanced editing programs.
.AVI: From what I know (and I'd like to point out I know a lot more about photography than video) this is a simple video format that has been around forever and from what I've seen is on it's way out from common use; I'd stay away from it more in favor of .mpeg4 or .wmv, which can take more advanced HD forms.
File size: When shooting in .jpeg, the T2i will give you a lot of options for file size; the default is large fine, which is 18 megapixels, or 5184x3456 pixels. This is way to big for frames of an animation. 1080p, the largest quality currently possible on youtube and with most editing programs, is 1920x1080 pixels, so you don't need to use this large file size, since most of the information will be removed when the video is rendered anyway. I am currently using the 60D, but will be switching to the T2i soon (yes, I'm down grading), and I use the small fine file size, which is still plenty big enough for full HD video (I always use fine, just to make sure I get the quality that I want).
Using a larger file size: Larger file sizes can be useful if you want a shot zoomed in further than your lens is capable of. If you shoot with a larger image size, you have tons of extra pixels left over, so you can crop the shot down pretty far and still have a full HD shot; I've used this technique before myself. I must warn you though, I'm not sure if this will work with your particular setup. I don't use a capture program at the moment, I just import frames from my camera, which I can then batch process in photoshop if I want to crop; you may not be able to do this, depending on the exporting options of DragonFrame.
I hope this was helpful. 