3. Easy debian will download an image file and store it where you tell it to IIRC. So it will be "installed" to where you told it to download to. The other option is of course to download the rootfs tarball that I believe Qole has floating around and extract that to an empty partition (there's that evil word again) on an SD card (any SD card, internal or external).

4. Most everything you asked is answered in qole's post..
4.1 In windows you are used to seeing C: and D: drives.. a lot of times that is the same hard drive - different partitions. A partition is just a separated space on a hard drive. The programs sfdisk and cfdisk help create partitions.. also I believe people got the gparted program working under easy debian that will also partition SD cards.
4.2 IMAGE_FILE is a setting in /home/user/.chroot that points to EITHER the Image File (yes, debian.img.ext) or the partition you made for Easy Debian (IE: /dev/mmcblk1p2).
4.3 - This was linked in qole's post, This outlines the step by step.
4.4 - Yes of course.. anyone can do it. There are several ways to do it.. But I don't have the tablet in front of me or a Linux box handy to get the exact syntax's so I'll leave that for someone else. You can use Tar, DD, or just cp -R from one location to another.

It would probably be a lot easier to help you if you outlined exactly how you wanted your END game to look.. and then we can tell you the process to go about getting there.