jmcarey: In the Filer.Thumbnailing configuration window you can set the 'largest image' maybe that also works for the image viewer (?).
What banner do you mean ? I have not seen the startup banner as I use the Germs (used to be part of BlackHole) to display a picture during startup. I think in this select release you just have to point a system variable to a picture of your choice to display it instead of the startup banner.