To answer your other question about two images on a canvas, here attached is a demo, using two images and an html file in the assets. The canvas image is saved to either the root of the virtual sdcard or the root of the ASD, depending on which android version you are running.
If using this, the html file must be in the same directory as the images.
twoImagesOneCanvas.aia (37.2 KB)
The setting of dimensions for the images is explained here (but was for the entire canvas and not a sprite inside it)