Regarding Templates, yes the screen is 160 DPI so if you have a drawing progam that can export PNGs at a particular image DPI then use that, otherwise just thing of the native size of the Illiad is 768W x 1024H and you want to fit within that.
Now that being said, I've noticed the Illiad does some "expand to fit" in the notes area of the underlying PNG, (or shrink to fit) so you might have to play around a bit to get it to be the exactly right size (I've not done this enough to know what that is but its around 768 x 977 to leave room for the control widgets at the bottom. Also I find about 5 pixels of whitespace at the the 'top' or right edge if landscape, will keep your template on the screen, otherwise it seems to go off the edge there by a pixel or two. (You can see my template has a thin line just off the edge there)
No developer kit needed, this stuff works off the shelf, create a B&W PNG image, plug your Irex into the USB port, drag and drop it into the Notes folder. It shows up there. When you select it you will see it is the 'paper' for your notes.