How can I change the entry icons, and where can I get icons from?

You can drag or paste icons from any image. For example, if you see a cute icon on a web page, you can drag that image to the image well in Caboodle. Tip: you can switch applications in the middle of the drag, if you can't see the image well when the other window is on top of it: start dragging the image, then (with the mouse button still down) press Cmd-Tab to switch apps, and complete the drag.

You can drag any size image to Caboodle's image well; it will be resized appropriately.