Java SE (Java Platform, Standard Edition)

Hello,

I'd greatly appreciate some advice on how to adapt a GUI-based java application to Web Start. I should point out that I am a scientist first and a programmer a distant second, and my knowledge of java is currently limited to writing small desktop programs.

APPLICATION DESCRIPTION:
In a nutshell, my application is a GUI-based viewer for ~500,000 very small (~3kb) image files. (in case you're curious, they're pictures of mutant yeast colony phenotypes). I used JavaDB to make a small index of the image annotations, and I display them in various formats depending on the user's filtering selection.

DILEMMA:
Upon publishing a paper based on the data that can be browsed in the application, I'd like to make the data available online to other scientists. The catch is that any given user is likely to view only a small number of the 500,000 available images, so I don't want to force them to download 500MB worth of image files (i.e. I don't want to put the images in the jar file).

SPECIFIC QUESTIONS:
[1] Is Web Start the best way to meet my needs?
[2] How specifically would I handle the image files... store them on the server and fetch them using URLs?
[3] Am I getting in over my head? I currently know virtually nothing about web start....

Thanks a bunch for your time. A little nudge in the right direction should be all I need...